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4. Operational Issues & Troubleshooting

Attention all readers: Sorry for the fomatting mess below. At some point the site changed how it handles HTML in FAQs and this is the result. I'll try to get it cleaned up as time permits. -RadioDoc

Given the state of some "technical support" departments at some of the major DSL mass-market providers; it is sometimes useful to identify an ISP related problem specifically. "My e-mail is down" you tell tech support. "Well, no one else is having that problem" or "everything looks good at this end; let's format your drive!"

Sometimes it's a good idea to call tech support with a specific technical report. It helps to cut through much of the BS.

So, you are surfing along, and suddenly your browser complains that it can't find yahoo! Before you call your trusty ISP, poke around to see why the browser can't find yahoo.

You first bring up a dos window. Enter "ping www.yahoo.com" What you get back is "Unknown host www.yahoo.com." So, my computer can't turn a name into an IP address... DNS (Domain Name System) issue. Call tech support now? Nope, not yet! Let's see WHY yahoo is UNKNOWN first.

You search through those papers your ISP sent when you got the account, along with your setup notes and find that your DNS server is OK let's see if it is working!

You bring up a DOS prompt. Type "ping" and you get:

Reply from bytes=32 time=110ms TTL=53

Reply from bytes=32 time=110ms TTL=53

OK, so it "seems " to be up, but is it really up?

Let's look into it further. We will use windows telnet to look into this problem. Why telnet? Well, it exists on all windows boxes, and is free.

1) Using windows telnet: [CONNECT -- Remote System]

2) Under "Host Name" enter the IP ADDRESS of the target DNS Server,

3) Under "Port" enter the NUMBER "53" instead of the default "Telnet".

4) Click on "Connect"

Now, several things can happen depending on the status of the target DNS server.

What we are doing here is simulating what your client software (the browser in this case) is doing when it needs to resolve a name like yahoo.com into an IP address..

If you have a good dns connection at this point, the cursor will go home (the upper left hand corner of the telnet screen). You will not be able to type on the screen, but a "CONNECT -- DISCONNECT" will work, and disconnect you cleanly.

This means the target system responded to a DNS request on its DNS port 53. This can mean that something is wrong with your networking setup. Possibly the DNS servers have changed IP address, or your networking properties defining DNS server IP addresses have changed. It is not impossible, but improbable, that it could be your ISP's DNS server, or connectivity related issue.

If you have a bad dns connect, after you click on the connect button, either you will see a perpetual hourglass which has to be killed by task manager; OR the error "Connect failed could not open a connection to" will appear on your screen. This means that your ISP's DNS server is not servicing port 53. This indicates that the DNS server is down. Even though it can be pinged, it is not servicing DNS requests.

Armed with this information, you now call tech support, and report that their DNS server is down. You know this because it has a dead port 53! When will it be fixed? By the way, do you have an alternate DNS server I can use??

This same troubleshooting technique can be used to test other ISP related services. Most Internet services which your ISP provides can be tested this way.

Try using this technique on your ISP's Mail server, use the number 25 for the SMTP port (instead of 53 which is for the DNS port), see if they are up, see what it looks like when they are up so you will know the difference when it is down. Try their port 110 POP3.... 143 IMAP etc...

Check out your primary ISP server-provided services this way the next time you have a problem, or suspect that your service provider is not providing a particular service.

Then call them, and report your findings specifically. You will get better mileage from your broadband connection and better "service" from tech support if you do some of the homework yourself.

This FAQ entry written and submitted by bobrichards

Feedback received on this FAQ entry:
  • Bob Richards Could you confirm the following....For windows 7 users instead of using telnet one may use the application called "Remote Desktop Connection". In the Computer drop down menu enter Ottawa The telnet I get at the C:\ is not very friendly. Thanks

    2010-05-11 19:57:51 (Ottawa1 See Profile)

by RadioDoc See Profile
last modified: 2008-10-07 13:45:21

For port 110 POP3, you can actually read your e-mail with a sequence of telnet commands. This can be useful if a garbage message is "stuck" in your mailbox, and you can't read it any other way.

Open a telnet session to pop.sbcglobal.yahoo.com 110
(the space followed by the 110 is very important)

You should see something like the following:

Connected to pop-sbc.mail.yahoo.com.
Escape character is '^]'.
+OK hello from popgate(2.34.1)

You will type your entire email address in the following line:
user username@sbcglobal.net (or username@ameritech.net, if appropriate) followed by the enter key.

You'll see: +OK password required.

At that point, you'll type in pass followed by a space, followed by your password, and the enter key again.

You'll then see something like:

+OK maildrop ready, 176 messages (17515507 octets) (37344915 2147483648)

At this point, you have several commands available, each one followed by hitting the enter key.

list shows the position number and size in bytes of all the messages sitting in your mailbox.

retr followed by a space, and a number displays that message on your screen

dele followed by a space, and a number deletes that message from your mailbox

quit ends the POP3 session.

by RadioDoc See Profile

Just about all inexpensive light dimmers (wall switch type, turn knob type, X-10 lamp modules, line cord or built in a lamp type) all work the same way. Some AC/DC variable-speed motors used in consumer equipment like treadmills use the same basic devices to control the speed of the equipment.

They have an electronic device called a Triac that switches the AC power wave on with various timing throughout the cycle. Triacs act like a switch in that they can only be ON or OFF. So how does that dim a bulb?

Delivering full voltage cycle to a bulb generates full brightness. Reducing brightness requires either reducing the voltage or the duration the bulb sees the voltage. Dimmers use triac circuits because they are inexpensive and deemed "good enough" for the consumer market.

AC power in North America is delivered in a 60 cycle sine wave where a complete cycle lasts 1/60th of a second. (50 or 60 cycle in other countries) Each wave has a Positive half and a Negative half, so each half is at 1/120th of a second. A sine wave is nice, orderly, and fairly quiet in the world of Radio Frequency Interference (RFI). Most RFI-sensitive equipment knows how to filter 60 and 120 cycle hum.

A triac defaults to blocking current. At some time into the AC cycle, depending on how a person sets the dimmer, the triac is switched on and allows current to flow to the bulb for the rest of the half cycle. A sine wave starts at zero volts, climbs to its peak positive voltage, drops back down to zero, then starts its negative side where it drops to its peak negative voltage and goes back up to zero and repeats the cycle.
Click for full size

For a dim setting, the triac keeps the current off until well-after the wave passes its peak, and switches on to allow only the lower voltage side of the wave through. The bulb sees a pulse of the lower voltage side of the wave, and glows dimly. When the wave reaches its zero point the triac switches off and is ready for the next wave pulse.
Click for full size

Increasing the dimmer control tells the triac to switch on earlier in the wave, allowing higher portions of the wave through, delivering more voltage, and the bulb burns brighter.
Click for full size

After all this, how does this mess up DSL?

A regular sine wave is a fairly quiet waveform as things go. However, chopping the sine wave with the triac produces a modified waveform that is very noisy in the electronics world. Worst case is the triac about midpoint, when the wave is at its peak sends a jolt from no voltage to full voltage. While those bursts 120 times each second might make the bulb glow at half brightness, it also produces massive amounts of RFI. Better dimmers have circuitry that suppresses some of this RFI, but you get what you pay for. An $11 dimmer will not have $25 worth of RFI suppression built into it.

RFI is insidious. It can sneak around no matter what you do. As you vary the brightness, thus varying when the triac switches on in the wave, you also vary the RFI. Some brightness settings may not affect anything, while some other settings could totally wipe out your DSL.

Noisy RFI from dimmers can reach your computer or modem through the AC lines, but more likely by radiating from the AC lines to your phone line. Dimmers on full brightness can still radiate RFI if there is even the slightest chop to the wave. Anything that uses a triac (or its cousin the SCR) to control a power line can radiate RFI and cause problems. RFI can interfere with various sections of the spectrum needed for DSL, causing lower sync rates and throughput, and in some cases repeated interruption or even total failure to sync.

Motion detection lights outside, even if they dont dim, likely use triacs to switch on and off. Check wall switch dimmers and line cord dimmers. Check desk lamps and anything else that uses electronic control, including fans. If you suspect a dimmer/RFI problem, either unplug the device, or totally disconnect power from that circuit and see if it stops. Turning the dimmer switch to off may not be sufficient!

Depending on how the RFI is received, you might try re-routing the DSL line, making certain the run is on a twisted pair like Category 5 cable, or you might have to replace or eliminate the noisy dimmer. For more information on how to track down RFI, see this "How can I detect interference with an AM Radio?".

Lastly, if you suddenly start having sync or throughput problems and you suspect RFI might be the cause, check and double check for anything around the home that has changed. Don't just assume that because you have not changed your computer setup that nothing is different. Did you have guests that visited and used the dimmer lights in a little used guest room? Did you just fix the attic fan? Did you install a motion sensor light on the garage? Did you get a new electric grill? It can be using triacs to control the heat. Sometimes RFI is hard to spot, but it can be solved.

by Riss_Centaur See Profile edited by lev See Profile
last modified: 2006-03-30 15:25:51

Adapted from a post by Jan Janowski See Profile

DSL uses some of the same frequencies as the AM radio band, so you can often use a portable AM Radio as a detection device to track down the source.

Tune your AM radio to a quiet spot in-between stations. There must be no radio station signal for this to work. You might have better luck finding one below 1200 KHz.

Now you can "Go Sniffing" for an interfering signal.

A few of the more likely causes might be:

A two wire outlet that has reverse polarity.
An incandescent light bulb
A fluorescent light assembly
Flashing lights, such as Christmas decorations
A light dimmer... even when the lights are off.
A microwave oven
A timer motor for lights or watering the lawn
A television
A motor (a fan in a bathroom, furnace, oven, or ceiling)
A transmitter (Ham or CB)
A darkness sensing outdoor light, even at a place down next door

If you believe you've found the source of interference, check your DSL and see if the problem is still there. If it is, turn the suspected device off and see if the problem goes away. If the problem is still there, keep going! You might have two sources of interference to deal with.

You will probably need to spend quite some time scanning until you find the source of your woes.

Here's how to fix the problems listed above. Re-scan after every fix.

If it is a two wire wall plug... REVERSE THE PLUG!!! On over half the interfering devices I've found, reversing the polarity of the plug resolves the RFI.

If it is an incandescent light bulb, REPLACE THE BULB.

If it is a florescent lamp assembly, first try new lamps, and then check the wires to the ballast (white is neutral, black is 'hot'). If that fails, replace the fixture.

If it is a flashing light string, obviously, REPLACE THE LIGHT STRING!

If it is a dimmer, check wiring on dimmer... If that tests okay, REPLACE THE DIMMER.

IF it is a microwave oven, TAKE THE OVEN IN FOR AN EMISSIONS TEST (if your store or repair facility doesn't understand what one is, go elsewhere!)

If it is a timer motor, REPLACE THE TIMER.

If it is a a TV with a three-prong cord, MOVE the television. You might also want to try an RFI/EMI AC Power filter box.

If it is a DC Motor, the coils are probably arcing. If it is an AC motor, it might be the AC start capacitor.

If it is a Ham or CB transmitter, use some diplomacy. Laws and theory are in the Ham's favor because of their FCC license. Approach the person and ask if he/she add a low pass filter to his/hers transmitter. That is about all the FCC will request on your behalf. RFI from transmissions will usually be within a maximum of 500 feet, so don't travel a mile looking for an RFI problem.

Should all the above fail, there are few other things you might try.

Visit Radio Shack and get a "Clip-on RFI Filter". It is a Ferrite core split in half, and you clip it on to the wire that's acting like a receiver. In 'mild' cases, tin foil around the wire will work. You'll also want to ground this wire to an AC outlet cover hold-down screw, or heat radiator. What you are trying to do is provide the interfering signal a convenient path to ground and eliminate it, without doing the same thing to the DSL signal.

Warning Will Robinson!!! This is a Black Magic Art....
What works today, may not work tomorrow....

Sometimes, a small amount of attenuation of the desired (Received) signal is "acceptable" in order to eliminate the offending signal. Since we don't have access to diagnostics, this part is definitely based on skill, experience, and luck. Just make certain that by winning the battle, you don't surrender the war.

Feedback received on this FAQ entry:
  • A low pass filter on a ham or cb transmitter will not help. DSL is lower than those frequencies. Low pass filters are for TV interference. The ham or cb transmitter issue is due to fundamental overload. CB is limited to 5 watts, and ham radio to 1500 watts. If it is CB, the FCC will be able to do something if the transmitter is running more than 5 watts (this is pretty common). It will be a task to get the FCC to take action. If it is a ham transmitter running up to 1500 watts, then you will need to find a DSL filter that is specifically designed to attenuate frequencies above 1107 kHz. Such filters are not included on DSL modems because they would add to the cost and are seldom needed. However, it's still your responsibility to filter out the legal signals that are interfering with your modem.

    2012-11-21 07:51:14

  • When the FAQ says "DSL uses the same frequencies as the higher end of the AM radio band" it is in error in that DSL uses the lower part of the AM band (138-1107 kHz, 224 downstream bins (32-255) ). So I would tend to find a quiet frequency at the lower end. But note that you would be looking for broadband noise-- which would be expected to hit frequencies throughout the band. So finding a "quiet" channel is most important in the procedure. Also, change -beteween" to "between".

    2009-05-29 08:40:34 (StillLearn See Profile)

  • I had the same problem with my treadmill and adsl. The RFI interference from the treadmill was being transmitted up the power wires around the house and passing the interference in to the telephone lines. I resolved the problem by plugging the treadmill in to a Belkin PureAV surge protector. Apparently, its "Power Filter Technology (PFT) isolates contamination to prevent AC and EMI/RFI power distortions". Whatever, it resolved the problem perfectly. Obviously, you would need the correct (voltage) version of this product for your country. http://www.amazon.co.uk/Belkin-8-Socket-Isolator-Protector-Composite/dp/B0002TSU9W

    2008-11-03 05:23:08

by RadioDoc See Profile
last modified: 2009-05-29 11:26:55

Line humming noise is either caused by radio frequency problems or faulty electrical equipment. RFI can cause problems with DSL. The power company is regulated by the state public utility commission. Here is a link to an article explaining what it can do to communication equipment.

by armyrebel4 See Profile edited by lev See Profile
last modified: 2003-12-04 04:04:59

This applies only to anyone who meets both the following specific qualifications:

1. Service through a remote terminal
2. The AT&T DSL Pro package, providing down sync of 1536-3008 and up of 384-512

Anyone upgrading from Pro to AT&T's elite package should set their RWIN values back to default.

Profile using Windows XP or 2000 having a speed issue who is past the 10-day ramp-up and achieves sync rates of 3008/512 but only sees 1.9-2.2 Mbps speed down at »help.sbcglobal.net/dsl/speedtest . If you do not see a sync rate of 3008/512, it's a seperate issue. Your line must also be served by a remote terminal for this to be of use.

Download DrTCP here. Get the top most file. Use it to change your RWIN setting to either 14520 to 17424. Try one first, then the other. 15972 is another good setting to try if you don't see results from the those two

Then change Top Receive Window to 14520, 15972 or 17424 and hit the apply button. Restart your PC.

Test your results with »help.sbcglobal.net/dsl/speedtest

If all is well, you should see between 2.3 to 2.5 Mbps.

You can also test with Optimum Online. Click on »ftp://ftp1.optonline.net/pub/test64 and allow it to download at least 15% of the file. You should receive between 280-312 KB/second, depending on internet traffic. At times of heavy traffic, this number can be far lower, but if it's consistently low over the course of several days, post about it in the AT&T Midwest Funhouse forum here.

This will be required for each computer you have running Windows 2000 or Windows XP. Older versions of Windows, Macintosh computers running OS X, or other machines running Linux do not have this problem.

by gdm See Profile edited by lev See Profile
last modified: 2007-06-19 17:27:18

Sorry to see you're having DSL troubles. Hopefully you have access to a different means of connecting, such as dial-up, in the event this does occur.

So you're ready to post in the forums about connectivity problems? Before you hit that submit button, there's some basic information that you can hunt down beforehand, which will greatly speed up our ability to figure out what's going on.

You may want to familiarize yourself with these steps, and download any recommended programs, PRIOR to having problems, so that when and if you do, you'll be prepared.

Here's a breakdown of what we find useful when you post a problem. Instructions on finding out some of the 'more detailed' aspects follows.

Type of connectivity problem (such as: can't access all sites, or some sites, or DSL is crawling, etc.)

When the problem started happening / when it occurs / any patterns to when it occurs

Redback Number

Traceroute OR Ping Plot (prefer Ping Plot)

Your setup (such as, are you using a firewall, or a router, or plugging direct from the modem into the back of your computer)

Operating System

DSL Modem brand and model

Now we're not going to need every single one of those for every problem, and we may even ask for more information, but this gives you a basic idea of what helps us help you.

And now for the detailed information:

YOU MUST PERFORM THESE STEPS WHILE CONNECTED TO THE INTERNET THROUGH YOUR DSL LINE. Performing the steps explained below while using a backup connection will not provide the same information.

Obtaining your Redback Number

This sounds difficult, but it really isn't. There's a FAQ in place that explains a Redback »AT&T Midwest/Ameritech FAQ »Redbacks. Love 'em Hate 'em Learn about 'em here so we'll concentrate on finding out which one you're on.

Your Redback number can be obtained by performing a traceroute from 'the outside world' back to your connection. (You do not need to be pingable for this test.) One site that makes this process easy is located here: »www.network-tools.com/

Your IP address should already be entered, so just click the 'trace' radio button, and click the 'submit' button. Once the trace is complete, you should see a readout similar to this one:

router.fifi.org 0% 1 1 5.83 5.83 5.83
dsl081-246-001.sfo1.dsl.speakeasy.net 0% 1 1 82.28 82.28 82.28
border5.g3-4.speakeasy-29.sfo.pnap.net 0% 1 1 84.93 84.93 84.93
core2.ge2-0-bbnet2.sfo.pnap.net 0% 1 1 74.42 74.42 74.42
POS2-3.GW4.SFO4.ALTER.NET 0% 1 1 57.43 57.43 57.43
162.ATM3-0.XR1.SFO4.ALTER.NET 0% 1 1 59.99 59.99 59.99
0.so-0-0-0.XL1.SFO4.ALTER.NET 0% 1 1 45.12 45.12 45.12
0.so-5-0-0.XL1.SCL2.ALTER.NET 0% 1 1 54.29 54.29 54.29
0.so-5-0-0.BR1.SCL2.ALTER.NET 0% 1 1 45.88 45.88 45.88
sl-bb20-sj-6-1-1620xT1.sprintlink.net 0% 1 1 37.83 37.83 37.83
sl-bb21-sj-15-0.sprintlink.net 0% 1 1 189.48 189.48 189.48
sl-bb24-chi-3-0.sprintlink.net 0% 1 1 69.26 69.26 69.26
sl-bb23-chi-14-0.sprintlink.net 0% 1 1 85.72 85.72 85.72 0% 1 1 78.45 78.45 78.45
sl-sbc-100-0.sprintlink.net 0% 1 1 75.87 75.87 75.87
dist1-vlan30.sfldmi.ameritech.net 0% 1 1 76.07 76.07 76.07
rback4-fa2-0.sfldmi.ameritech.net 0% 1 1 85.86 85.86 85.86
adsl-66-73-xxx-xxx.dsl.sfldmi.ameritech.net 0% 1 1 102.13 102.13 102.13

Note the second to last entry. This line will tell you your Redback number, as indicated by rback#-(insert rest here). In this example, the Redback number is 4.

For those that know their IP address, or can obtain it quickly, this second site may also be of benefit, especially if you have problems accessing the first one. (This is the site used to perform the trace above.) »www.fifi.org/services/traceroute

This site isn't as graphically intense, so loading it would be easier during periods of slow access. Plug in your IP address, and click the 'submit' button.

Traceroute Information

Note: We find a Ping Plot much more useful, as it contains the same information a traceroute does, along with additional information. These traceroute steps should only be followed if it is not feasible for you to download a ping plot program, such as when your connection is slow.

This is performed in the same manner as what was used to obtain your Redback Number, except in reverse. You're going to traceroute to the site you're having problems accessing. Traceroute results will show how your connection to a specific site is being routed across the Internet, and where in this connection is having problems.

Programs such as McAfee Visual Trace (NeoTrace to us long-time users) can perform both a traceroute and a Ping Plot (explained later). If you use a program such as these to post your information, please only post the sections pertaining to the traceroute, and the ping plot. Don't post the breakdown about each server.

For this FAQ, we'll use the traceroute program that comes with each copy of Windows, called tracert. You'll need to open a DOS prompt. Click Start, then Run. Windows 95/98/Me users will type 'command', while Windows NT/2000/XP users will type 'cmd', without the quotes on both, and then press OK. If the DOS session takes up the whole screen, where you can not see the taskbar in Windows, press ALT + Enter to bring the DOS session back to a window.

Once at the DOS prompt, type the following:

tracert (insert site here)

where (insert site here) is the site you're having problems accessing, and press enter. For example, to perform a traceroute to dslreports.com, you'd type

tracert www.dslreports.com

and press enter. Your results should be similar to below:

Tracing route to dslreports.com []
over a maximum of 30 hops:

1 17 ms 18 ms 18 ms adsl-66-73-xxx-xxx.dsl.sfldmi.ameritech.net [66.73.xxx.xxx]
2 18 ms 18 ms 18 ms dist1-vlan50.sfldmi.ameritech.net []
3 17 ms 18 ms 18 ms bb1-g2-0.sfldmi.ameritech.net []
4 23 ms 23 ms 23 ms sl-gw34-chi-2-1.sprintlink.net []
5 23 ms 23 ms 24 ms sl-bb21-chi-4-3.sprintlink.net []
6 24 ms 23 ms 23 ms sl-bb24-chi-9-0.sprintlink.net []
7 45 ms 44 ms 45 ms sl-bb26-nyc-14-1.sprintlink.net []
8 43 ms 44 ms 44 ms sl-bb20-nyc-15-0.sprintlink.net []
9 45 ms 44 ms 45 ms
10 46 ms 47 ms 47 ms tbr1-p012402.n54ny.ip.att.net []
11 46 ms 44 ms 45 ms gar1-p3100.nwrnj.ip.att.net []
12 51 ms 49 ms 50 ms att.ge-0-0-0.gbr1.nwr.nac.net []
13 49 ms 49 ms 50 ms 1189.at-0-1-0.gbr1.oct.nac.net []
14 53 ms 51 ms 52 ms 0095.gi-1-1.msfc1.oct.nac.net []
15 52 ms 54 ms 51 ms www.dslreports.com []

Trace complete.

Now, to copy and paste these results, the best method is to first paste into something like Notepad, clean up any formatting problems, and 'xxx' out your IP address's last two numbers, as shown in this example, in both the resolved name, which is the information before the actual IP address, and the actual IP address, which is in brackets.

To copy the contents of the DOS window, right-click on the taskbar's entry for the DOS window, select Edit, then Select All. Then press Enter. You can then paste the traceroute information into Notepad.

Ping Plot

This is extremely similar to a traceroute. If you perform a ping plot, performing a traceroute as shown above is not needed, as this will already perform that. A ping plot is preferred over a traceroute, as it contains the same traceroute information, along with much more.

You'll need a program which can do this. McAfee Visual Trace can perform this function, but posting its results is very difficult, and it's difficult to read on the forums. For this reason, we'll use a different program called Ping Plotter Freeware, which can be downloaded from »www.pingplotter.com/download.html

Once this is installed and open, you can put the site name in the 'Address to Trace' box. The settings below can be adjusted to your liking, but for our testing purposes, the following will do:

# of times to trace: 30
Trace Delay: 2 seconds
Samples to include: ALL

On the right side, which should be completely gray at this point, you need to right-click and make sure all items have a check mark. Once this is done, click the 'trace' button and wait for it to finish. (You'll know it's done when the Stop button switches to Resume.)

To post your image, you'll need to save the image. Click Edit, then Copy as Image. Open Paint and paste your image. Before saving, you should edit-out your IP address information by using the eraser, or painting over it. Then save the image as a .PNG file (we prefer this) by clicking File, then Save. Switch the Save As field to show PNG.

To post this image, click the 'Got Attachments?' link, and use the Browse button to locate your image, and add it to your post. You can still post a message with your image, too.

by ahulett See Profile edited by lev See Profile
last modified: 2003-03-05 16:45:27

W2K - Gracefully Handling Internet Outage


Broadband Internet access is generally reliable, but outages still occur. When they do, you might experience a problem with your workstations no longer seeing your broadband router.

For example, let's say you use a DSL broadband connection and your service goes offline for an hour or so. When your service comes back up, your workstations can no longer access the Internet. You could reboot the workstations to get them back on the Internet, but there's a much easier solution: Disable Media Sense in Windows.

The Media Sense feature in Windows 2000 allows Windows to detect the link state of a network connection. When Windows detects that the link state is down, Windows unbinds the protocols from the adapter until it redetects an up state. This behavior can prevent Windows from gracefully handling an Internet outage. By turning off Media Sense, you prevent Windows from unbinding the protocols, and eliminate the need to reboot when the service comes back online.

Here's how to disable Media Sense in Windows 2000 Professional:

First, open the Registry Editor and open:



1. Add a DWORD value named DisableDHCPMediaSense.
2. Set the value of DisableDHCPMediaSense to 1.
3. Close the Registry Editor and restart the computer.

Media Sense makes it possible for Windows 2000 computers to disconnect from one network and detect new settings when you connect it to a different one. If you don't move your computer between networks, disabling Media Sense can simplify your life when Internet outages occur.

If you do move your computer between networks, you might eventually need to set the value of DisableDHCPMediaSense to 0 to re-enable the feature.

REMINDER: Editing the registry can be risky, so be sure you have a verified backup before making any changes.

From techrepublic.com.

Feedback received on this FAQ entry:
  • was that "1" a binary or hexadecimal value?

    2008-10-21 14:23:26

by alturner See Profile edited by lev See Profile
last modified: 2004-01-01 22:00:54

For first time installations, you want to make sure that you are installing your modem on or after your service activation date. However, most DSL orders may have sync several days before the due date. No sync means you have no dsl signal or the dsl signal is too weak to maintain a connection with your modem.

The modem currently being shipped for new customer self-installations is the Motorola 2210.
On the 2210,4100 and the 5100b modem, no sync is indicated by the DSL light flashing red.

When there is sync the DSL light will flash green it may also briefly flash red before it goes solid green indicating the the modem has sync and is trained.

If the 2210, 4100 or 5100b modem is configured for "PPP is on the modem" the Internet light will flash green while it's authenticating the username and password, once authenticated the Internet light will go solid green.
Also the Internet light will flash red if authentication fails on either end.
If the 2210, 4100 or 5100b modem is configured for "PPP is on the computer" or "Bridged mode (PPPoE is not used)" the Internet light will remain unlit.

1) Verify with AT&T HSI that the correct phone number was set up for DSL. If you have more than one phone line in the home, it is not uncommon for the wrong line to be provisioned with DSL.

2) Check your connections. Be sure to plug the modem into the line you ordered DSL on, it will not work on other phone lines. Plug the DSL modem straight into the wall jack with no filter.
Make sure all phones, analog modems, fax machines, and any other devices that use the DSL/phone line is plugged into a filter before it's plugged into a phone jack. Occasionally, you could get a bad filter. If you can get sync without the 2 port filter but lose sync with the 2 port filter on the modem line, then your 2 port filter is bad. If you have only one jack in the room and need to use the 2 port filter, try another. Any device attached to a phone jack needs a filter.
The DSL modem does not need a filter.

3) Be sure to use the data cable/phone cord that came with the modem. Sometimes, the regular flat phone cord will work fine for your DSL modem and sometimes it won't. These cords can get damaged easily and could work for dial-up and not for DSL. Someone can use a 100 ft flat phone cord and sync up just fine. Others can have a 5 ft cord they have used for years that won't allow DSL to sync up.
If you plan on using a cord other than the data cable/phone cord that came with the modem....Don't, you should consider purchasing a longer CAT-5 patch cord with RJ-45 jacks at both ends from a computer store or Radio Shack to replace the short yellow CAT-5 patch cord.

4) Verify that you do not have anything such as a home security alarm, doorbell, water meter, or other devices on the DSL line that could interfere with sync. If you do, you will need a pots splitter to filter all the house wiring and install a dedicated cable connected before the pots splitter and jack for the DSL modem.

5) If all the above checks out fine, then you may have a line problem, there is one more step you can take to isolate the problem to your house wiring or to AT&T HSI's wiring. Take the modem to the NID and connect the modem to the test jack on the customer side of the NID.
NOTE: When you disconnect the RJ11 jack at the NID you'll be disconnecting all house phones.
If the modem can sync at the NID test jack that shows a problem with the house phone wiring.
If the modem cannot sync at the NID test jack that shows a problem with AT&T HSI's part of the wiring.

Graphic by Riss_Centaur See Profile

by wayjac See Profile
last modified: 2008-01-23 15:34:35

Item 2 does not apply to modems shipped since early 2004.

If you have sync (solid green light on 4060 | 4 green lights on 5260-actually just DSL and ATM, but you need ENET to be green anyway | Solid green Power, Ready and Link light on Westell Wirespeed, DSL light solid green on other products) and this is a new DSL order, then verify the following:

1) Right-click on the DSL Connection profile, select Configuration, and verify that the correct adapter is chosen. If you use the 4060, this would be the 4060. If you use the 5260 or Westell Wirespeed, verify that you have chosen the NIC that the DSL modem is using. If your NIC is not an option in the adapter list, it may not be installed properly or tcp/ip might not be bound to the NIC in the Network settings(Start-Settings-Control Panel-Network).

2) Create a new profile and try to connect.

3) You are probably not mapped in the router. Call the SBC Customer-Self Install department at 877-722-3755 for problems with installation. They can call the ASI Test & Turn-up dept to verify or input the router mapping if it's non-existent.

In rare cases, you could be wired to the wrong DSLAM port and would receive sync on that port but that port would not be configured to hook up to a router. It could also be your NIC. For example, the 3-Com integrated ethernet port on the Dell Dimension 4100/8100 has caused many people to get a "Connection Time Out". You can use the Kingston Ethernet card that came with the kit if this happens.

by Ranma See Profile edited by lev See Profile
last modified: 2005-03-02 15:42:18

If you find your DSL modem drops offline or loses sync when your phones are not in but syncs okay when you use the phone, you have a condition likely caused by a high-resistance open, or "high open".

The phone line consists of a pair of copper wires originating at a Central Office (CO) or Remote Terminal (RT) and running through various cables, cross connect boxes, and other splices until it reaches your Network Interface Device (NID). From the NID your inside wiring brings the line to your telephone and modem jacks.

Each splice, interconnect, and terminal on the line between you and the phone company's equipment must be a tight, low-resistance electrical connection for the line to work well.

When you use a telephone a small amount of electrical current flows in the copper wires and this current, which carries your voice, also helps keep the splice points in the line clean and tight. This is commonly called "sealing current" because it seals the junctions.

Lines exposed to air can either oxidize slightly or sometimes corrode heavily depending on conditions. This deterioration at splice points in copper phone cable can cause this "high open" condition. The bad junction creates high resistance, effectively creating an "open" in the line, and DSL signals might fail to cross it, or be weakened by the attempt. When a phone is picked up current begins to flow and the resistance drops during the call. If its just a light case of oxidation you may not notice any change in sound quality. A bad case of corrosion might cause audible clicks, pops, and static on a voice call.

Since DSL signals do not draw current on your line, high open conditions can lead to the degradation of the DSL signal to the point of losing sync. When you use your phone you seal the faulty connection and DSL signal returns. When you put the phone on-hook and stop the current flow the high open returns, sometimes right away - sometimes with a delay, and your DSL loses sync. High opens can also cause other oddball conditions, such as sync loss when the phone rings.

To fix this situation you should first test NID your modem at your NID. Plug your DSL modem directly in to the test jack at your NID and see if sync is solid there.

If you do not have good sync at your NID then you need to call your phone company and report trouble on your line. It is recommended that you first report it simply as a Plain Old Telephone Service (POTS) problem of "static" on the line and request a metallic loop test. This is the automated test done when ever a phone line problem is reported using the normal phone trouble number. It should spot a high open condition. If you talk to a trouble operator do not mention anything about DSL at this point, it only serves to confuse the issue sometimes.

If the test spots the high open problem the telephone company will track it down and fix it, which should lead to normal DSL function again.

If you do have solid sync at the NID, then the problem is someplace in your inside phone wiring. Check all the screw terminals at the NID for tight wire connections. Check any splice points in your internal wiring for corrosion or bad junctions, especially in moist or damp areas. Disconnect any lines to jacks that are no longer used and double check all wires in jacks and look for clean contacts on plugs and sockets. Plug a phone in at your modem's jack and make sure you have clear dial tone and no static.

If this does not solve the problem then start your DSL service provider's trouble procedures.

by Riss_Centaur See Profile edited by RadioDoc See Profile
last modified: 2013-02-04 20:41:16

This is never caused by the server or a sync issue its always caused by a communication problem with the server when the tcp/ip protocol is disabled or missing for the NTS PPPOE adapter.

In Win 98/ME/2000, go to Start-Run, type ASD, click Ok. If you see tcp/ip for the NTS PPPOE adapter here, put a check by it to enable it, and reboot. You should be able to connect now.

If that doesnt work, then the NTS PPPOE adapter may be missing tcp/ip. Go to Start-Settings-Control Panel-Network. You will see that there is no tcp/ip protocol for the NTS PPPOE adapter here. Win 95 allows a limit of 4 adapters with tcp/ip bound to it and Win 98/ME allows a limit of 6. If you have more than the limit allowed, then you will have to remove any unneccessary adapters that listed here. If you have AOL 6.0 and do not use it, then uninstall AOL 6.0 because it uses up 3 tcp/ip stacks for AOL Adapter, AOL Dial-Up Adapter, Dial-Up Adapter #2 (VPN Support). Once you have removed the excess adapters, you can add a new tcp/ip bound to the NTS PPPOE adapter by going to Add-Protocol-Add-Microsoft-TCP/IP, click Ok. When you see the NTS PPPOE adapter is bound with tcp/ip, click Ok and reboot your PC. Try and connect.

by Ranma See Profile edited by lev See Profile

Blue/Black oxidation corrosion formed on gold contacts inside plugs.

As noted in this forum thread: »forum/remark,14316716 inconsistent DSL connections can be due to faulty phone line connections. This can happen at jacks and filters, especially in wet or damp locations, and also in locations that seem dry but have high humidity.

This type of issue can usually be caught with the NID test (»faq/4787) because it would bypass all inside house wiring. But if you experience decreased DSL speed, lower noise margins, or static on the phone line, it is always a good idea to make sure that all phone plugs and sockets are free of corrosion everywhere in the house. Even if a plug or jack is not directly connected to the DSL modem, corrosion in any part of the phone line system can lead to shorts and signal degradation. Replace or clean thoroughly any plug, jack, filter, or terminal block that show signs of problems.

Thanks to derek5240 See Profile for the picture above.

by Riss_Centaur See Profile
last modified: 2005-09-08 11:52:39

Common causes of DSL troubles inside the home

1. Filters

Filters, filters, filters... Check for missing, defective or incorrectly installed filters. Filters need to be plugged into the jack first and then the phone plugged into the correct port. Filters can cause sync issues if installed backwards. All equipment except the DSL modem that uses the DSL line needs to be filtered. If you need to have a filter at the same jack as the modem, be sure to plug the modem into the correct side of the filter. Sometimes a filtering issue will not be noticeable and work for years on lower speed packages that get a strong enough signal, but then problems will often occur when upgrading to a higher speed package.

These are some of the often overlooked devices that need filters - dish receivers, dialup modems, alarm systems, phones in the garage, basement or outbuildings, outdoor or extension ringers, some types of water meters and some types of secured entry systems also use the phone line. In some instances a splitter install and home run will be needed to provide proper filtering, usually in situations involving alarm systems, water meters and secured entry systems.

2. Infected Computer

At a bare minimum, make sure to regularly update the operating system and perform virus scans on a regular basis. Infected computers can cause a range of problems that are often confused to be DSL problems, slow speeds, high ping times, etc..

Some free programs to try are Ad-Aware and Spybot S&D. These programs can sometimes find items that your regular virus scan doesn't find.

Ad-Aware www.lavasoftusa.com/software/adaware/

Spybot S&D www.safer-networking.org/en/downdex.html

3. Firewalls

Some firewalls, ZoneAlarm is a known example, need to be configured properly to prevent problems accessing the internet. To eliminate this as a possible problem depends on if it is a hardware or software firewall. For hardware firewalls, set up the computer to connect directly to the modem. For software firewalls, disable or shut it down temporarily. If the problem goes away, then the firewall is suspect. If your network contains multiple computers, switches, etc.. you either set it up yourself and know what your doing or you better call someone that knows what they are doing.

4. Customer Equipment

Usually routers are the main culprit, due either to improper configuration with the modem, firmware issue or a hardware failure. Common issues are intermittent surf, connection problems and slow throughput. Set up the computer straight to the modem, if it works ok that way, then the router is suspect. Other common problems involving hardware connectivity are defective network cards and patch cables.

Surge protector power strips with phone line ports sometimes cause problems, make sure the DSL modem phone cord is plugged straight to the jack and not through one of these power strips.

Some older 2.4MHz cordless phones can also cause issues with wireless connections. If you have one of these, unplug it and see if the issue goes away. If so, move the phone as far away as possible from the wireless equipment, otherwise try replacing with a newer phone in the GHz range.

Some rare bizarre things in the home or even a neighbors home can affect DSL. Dimmer switches, treadmills, motion detector lights, defective or failing television sets and monitors can potentially cause intermittent problems. These types of problems are usually rare, are difficult to isolate and involve a good amount of head scratching.

5. Defective Modem

You usually receive a modem from your DSL service provider. Like it or not, the modem is ultimately your equipment unless specified otherwise by your provider. Warranties and replacement policies also vary depending on provider and manufacturer. The average lifespan for most DSL modems seems to be around four years. The usual ways to determine if a modem is defective is to try the connection with a different computer, or borrow a modem and see if your problem persists with the borrowed modem.

If you are sure that the modem is defective and under warranty, call your provider for a replacement. If no longer under warranty, they can be purchased at electronic stores such as Best Buy, Circuit City, etc.. otherwise, call your service provider for either a replacement modem or a tech visit.

Note: Most service providers do not provide technical support for modems that they do not sell or provide.

6. Defective Phone Jacks and Patch Cords

With a visual inspection you can usually tell if a jack or patch cord is defective. Check for loose connection and broken pieces. The other thing to look for is black or green stuff on or between the pins that indicates corrosion or a lightning hit. Most defective jacks and cords are found in basements or garages. Unless you live in a house where someone thought it was a good idea to put a jack in the bathroom or outside.

Avoid using flat patch cords if at all possible with your DSL modem. These types of cords are very prone to interference, often very poor quality and can cause many sync issues with DSL.

If you are handy, a multimeter can be used to determine if a cord or jack is defective. If not sure how to do this, contact someone who does know before tearing the wiring apart and causing a bigger problem.

Jacks and cords are cheap and generally easy to replace. If in doubt, change it out. Again, contact someone who knows how to do this if you can't figure it out.

7. Loose wiring connections

These can be difficult to isolate, but the usual culprits are taped splices and wire nuts. Other places to check are jacks, junction blocks and at the Network Interface or protector. Usual symptoms that you might notice during voice calls are static and erratic ringing. Do not use alligator clips for connectors, for some reason I keep finding more of this lately and it makes for a terrible DSL connection.

8. Excessive Inside Wiring

Generally, if you have more than 5 jacks on your DSL line, you could have excessive inside wiring which acts as multiple bridge taps that could possibly degrade your DSL by causing signal loss or reflection. In these situations, a splitter install and home run to the modem is recommended.

9. Poor Quality Inside Wiring

Ideally, you should have a minimum of category 3 grade cable for inside telephone wiring. However, most older and even some newer homes have quad cable originally installed. Quad wiring has four wires, red, green, yellow and black. Even older wiring has three wires, red, green and yellow. Older still is cloth covered wiring. If you have quad wiring or older, jokingly referred to as category 1 cable, can allow interference from outside forces (usually AM radio) to disrupt the DSL circuit.

Worse yet, is when people use other wire types as a substitute. Some of the wire I have seen used is speaker wire, thermostat wire, doorbell wire and among other wacky stuff an electrical extension cord buried to a garage. Usually duct tape and wire nuts accompany such handiwork.

A splitter install and home run normally is the easiest and most cost effective way to take care of these types of issues.

10. Corrosion

Usually these problems are found at jacks, junction blocks, and the Network Interface. However, the problem could be at any point that condensation can build up. Usual symptoms that you might notice during calls are static, hum, crosstalk and erratic ringing. Check your line at the Network Interface to determine if the problem is with your wiring. A multimeter or other test equipment is usually used to help isolate these types of problems. Again, if not sure how to do this, contact someone who does know before tearing the wiring apart and causing a bigger problem.


Thank you to MrFixitCT See Profile, nunya See Profile and Shadow01 See Profile for their help.

By Shortbus28

Feedback received on this FAQ entry:
  • I am a computer tech, it's been a while since I was called out to a DSL problem. Your info was spot on. THanks for the tips and the money it made. :) ROCK ON!!!!!!

    2009-04-09 12:03:20

by 59126125 See Profile edited by lev See Profile
last modified: 2006-08-05 10:54:13