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5. Troubleshooting
If you are getting stalls when using your PC before your new ADSL line has been activated, your new internal card (if any) could be attempting to talk to the network (which is not yet configured for you), and while it does this, your PC may freeze. The solution is to remove the drivers for the card and/or the card itself, until the ADSL line is activated by the Telco, then re-install from scratch. If your PC is freezing regularly, and you are on PPPoE, your computer may be looking around for a DHCP server that does not exist. Check the following: (Windows)
Also see this thread: Internet freezes momentarily while surfing. by mballard edited by KeysCapt Measuring your DSL speed is not easy. There are a number of speed test applications on the web (our contribution is here), and your ISP may suggest you try a single FTP download, or multiple FTP downloads. What to do? First, no single test is enough to determine the speed of your line. The internet has weather, as does your ISP, and the server you are downloading from. Weather can delay delivery, as any postman will tell you! Once you have concluded, perhaps by comparing others' results, that your speed is not what it should be, here is a check list of things to worry about if you have a DSL line. For cable users, we have an excellent cable FAQ that may help you identify coax noise that could be slowing you down. cable tech faq.
Feedback received on this FAQ entry:
edited by KeysCapt The most important thing you can do to your PC to maximize broadband performance is to optimize your MTU and RWIN values. Before you make any changes run a baseline speed test to a reliable test site and record your results...then get tweaking! MTU (Maximum Transfer Unit) MTU is the maximum packet size (in bytes) that can be transported reliably across any particular network; IP Ethernet in this case. The maximum size of an IP Ethernet packet is 1500, but overhead like IP, TCP, and PPPoE must also be taken into account. The wrong MTU will actually prevent you from accessing some web sites or FTP sites. It may even cause you to not authenticate properly on mail servers or secure web sites. There are too many variables to be able to estimate what your optimum MTU should be, but there is an test that can determine your correct MTU. Important Notes: •If you have a network with multiple PCs every computer should be set up with the same MTU. Additionally, some PCs may use several Network Adapters or a VPN client adapter on one PC so you must verify you are changing the Network Adapter associated with your broadband service or VPN client. •Due to additional overhead, some VPNs may require an MTU that is much smaller than the results of the ping test. The best way to eliminate MTU as a possible source of the problem is to lower the MTU to 1200 and test the VPN connection. If it functions correctly at 1200 increase the MTU until the VPN stops working properly and use the largest size MTU that did work. Additionally, some VPNs create separate network adapters so be sure to select the correct adapter when changing MTU size. • The built in PPPoE client for Windows XP uses an MTU that can not easily be changed or set manually. The MTU is set to 1480. For more information please reference this XP MTU article. This only applies if you are running the built in XP PPPoE client! Although the Broadband Reports Tweak Test offers very good general information, it may give erroneous or misleading MTU recommendations and its information should not to used. Since it simply looks at whether you use PPPoA or PPPoE, it can not give accurate, individualized MTU analysis. To guarantee the proper MTU customers should use the following procedure:
Change your MTU using DrTCP (see example below) or any similar registry editing application. Remember, you must change the MTU on the correct network adapter (if you have more than one) and you must reboot your machine in order for the settings to take place. RWIN (Receive Window) The TCP Receive Window can be thought of as the main data gate keeper to your computer. It sets the limits on the amount of data that can be received before it must send an acknowledgement and broadcasts that to the sender. If the number is too low you will tie up bandwidth with frequent and unnecessary acknowledgements. Too high of an RWIN will create a slowdown if any packets need to be retransmitted. There are mathematical calculations that can be used to obtain your optimum RWIN, but they are complicated and rely on variables that can easily change. I suggest using real-life testing with some guidelines from the Tweak Test:
Record the "MSS Requested" number (possibly 1452 or 1460) shown in the left column of the results. Note: All RWIN values should be an even multiple of your MSS. Change your RWIN to the highest recommended setting (roughly 37,000) using DrTCP (see example below) or similar registry editing application. Remember to change the RWIN on the correct network adapter (if you have more than one) and reboot your machine in order for the settings to take place. Retest your download speeds and record any changes. Retest again using the next higher or lower RWIN value until you find your optimum speeds. Note: When trying different RWIN values make sure you use even multiples of your MSS. For example: 1452 MSS x 26 Even Multiple 37752 RWIN The next lower RWIN value would be: 1452 MSS x 24 Even Multiple 34848 RWIN Changing the MTU and RWIN values You can download and use DrTCP or any similar registry editing application to change your MTU. An example of changing the MTU using DrTCP is shown below. (Figure 4) Pictures by Andy Houtz Note: If you have more than one network adapter on a PC you must change the MTU on the correct network adapter associated with your broadband connection. You must reboot your computer in order for the new MTU settings to take place. Additionally, if you have a network with more than one PC, all computers and the router must have the same MTU setting. Please reference the links below to learn how to change the MTU on some popular routers: Feedback received on this FAQ entry:
by Andy Houtz edited by KeysCapt All of a sudden, your computer is not online any more. What basic steps can you take to diagnose what is wrong? A variety of problems can be the cause of "net down". The first thing to check is power, lights and connections. If there are lights to check, are they all green? If they flash with activity, are they flashing when you attempt to use your browser? The modem may be trying to tell you something. Refer to your manual on lights or status information. If you're running Microsoft Windows, a reboot is often the first thing to try unless you have evidence that the problem lies elsewhere. General tests are, first, try to ping a well known server, like Netscape. Open an MSDOS prompt, type ping www.netscape.com and press return. NOTE:(Make sure the server you pick to ping responds to ping! Many servers now do not, and you should not confuse that with a network problem). If you cannot resolve the name to an IP address (ping will hang for a while or may fail with cannot resolve hostname type errors), then ping a known good IP address. The IP address of your local ISP is a logical start. It is always useful to have some key IP addresses jotted down for simple diagnostics like this, unless you have a good memory for 4 part numbers. If you can ping an IP address inside your ISP, congratulations, it is not your DSL line. If it is your DSL line, you may be able to call the ISP and get them to try to ping you, which should start them on solving your case, otherwise your ISP maybe able to inform you of a network problem they are having. by KeysCapt Wait for your install date. Be patient and it may come on early. Check the filters on the devices. EVERYTHING but the DSL Modem on your DSL phone line MUST have filters or it may keep you from getting sync/not be stable/slow. Don't forget items such as the phone line into your cable/satellite TV decoder, etc. by Tibby edited by KeysCapt There are a few things could cause this. Your DSL modem may be malfunctioning. If this is the case you should call your ISP and tell them to replace your modem, or, if the modem is yours, either have it serviced or replace it. In order to determine whether the problem is inside your home or outside, take your modem to the NID (Network Inteface Device) and connect directly. This eliminates any inside wiring. If you are able to sync up fine outside of your house at your Telephone box (more commonly known as the NID, Network Interface Device) Then your inside wiring will need to be inspected. You will have to notify your telephone company and tell them to fix the problem. Note this will cost you money because it's outside of your ISP/DSL service. Your telephone line could be losing quality. Line noise, electronics on the line, or a short on the line can break up a sync signal. You will have to tell your ISP that you keep losing sync and want to have your line checked for problems. They should open a trouble ticket with your ILEC/CLEC and they will inspect the lines. In most cases they can find the problem this way. by Masamune edited by KeysCapt This is a symptom of bad internal wiring, or problems with filters, splitter or sockets. Another possibility is an MTU on the line. An MTU, is a Maintenance Test Unit. In days long gone, it was used to remotely check for problems on your phoneline. It seems these lovely units that consist of an Op-Amp and a bunch or resisters, capacitors, etc ... cause major problems with DSL. These are generally located in your phone closet or basement (where the phoneline comes from the street into your house/apartment). You can have your phone company do a line check and they should be able to determine if you have one on your line and approximately where it is located. Some other possibilities suggested by our members: 1. If a customer's DSL goes out when they answer an incoming telephone call, it's not always in the house wiring. Have your local phone company check the CO for what we call a half tap. If they find one that should solve your problem. 2. If the water company's automatic reading unit in your basement is connected to your telephone line, it may be causing issues. Unplug the phone line attached to it and you can see if this is the case. They may contact you advising they can't read your water meter. You can advise them it is causing issues with your DSL and they will hopefully address the problem. Feedback received on this FAQ entry:
by Foosplayer edited by KeysCapt The usual answer to this is DNS resolution, or some problem with name resolution. When you give the name of a website, your PC must communicate to a DNS server to resolve it to an actual IP address. If your ISP is having DNS server difficulties, this resolution process may take time. Subsequent resolutions may be quicker because the ISP DNS server has now cached the name. If your DNS server exhibits very slow response, and consistently so, then contact your ISP to ask them to investigate. Another source of slow DNS queries is how your PC may be resolving the location (IP address) of the web address you enter. From an command line window, you can use the NSLOOKUP command to test name resolution speed. Pick a website that you have never visited (perhaps from a newspaper advert or something), then type 'nslookup name.of.site.com'. The delay before the IP address of that site is returned should be no more than a few seconds, perhaps for some small and slow websites, the delay could be 5 seconds or so. If the delay is consistently much longer for new sites than these estimates, your PC may be trying to locate the name of the site via several methods before your ISP DNS server is queried. (Windows) The cause for this is possibly the presence of a number of networking protocols and clients in your networking setup, which cause the PC to attempt name resolution first locally (using netbios), then via your ISP. The local attempt will fail, but not until after a timeout period. If you are in doubt as to which protocols may be safely removed, ask a question in our forums. by KeysCapt Some software installs, for example Enternet, can make MSIE lose knowledge that you are connected full time to the Internet.
------------- One of our visitors added this bit of information which might be of help to others:
Another added this:
edited by KeysCapt ADSL lines that are much faster download than upload do not do well when simultaneous uploads AND downloads are required. To operate the download channel at full speed, a large portion of the upload channel is required. If the upload channel is busy with something else, TOTAL throughput can drop severely as the competition for resources slows down both activities. Users have also reported that streaming video both in and out at the same time results in very poor throughput - much lower than one would expect looking at the speeds available. There is not yet any recommendation or information on what can be done to get around this problem, other than changing to a DSL service with more symmetric capacity. by KeysCapt First you must distinguish between Public IP address and Private IP address. Your public IP address is that which the world believes you are on. Your PC private IP address may be something else entirely. You may find your public IP address by using the BroadbandReports IP tool: /ip. Your private IP address is that reported by your PC. For example, in Windows, Start->Run->Winipcfg (or "ipconfig /all in a command line window)will bring up a utility that describes the IP address the PC has. Be careful, your PC may have several IP addresses! If you cannot ping your public IP address, it may be because the machine this represents simply does not respond to ping.If you cannot ping your private IP address, you may have installed a firewall that refuses to acknowledge ping packets. If neither of these cases apply, you may not have correctly identified your public or private IP address. Feedback received on this FAQ entry:
by edited by KeysCapt Your Windows 98 Second Edition Computer May Stop Responding or Experience Slow Download Times with a USB (Universal Serial Bus) Modem. This problem is resolved in Windows Millennium Edition (ME). »support.microsoft.com/di ··· ;q240947 You have to contact Microsoft Tech Support to get them to email you a download link to their FTP server for a "hot" fix mentioned in KB article Q240947. by EmbeddedEric edited by KeysCapt If you are using PPPoE and you experience a long delay after rebooting, your network adapter may be configured to use DCHP. Try assigning an internal IP address to the Local Area Connection that corresponds to your network adapter. Control Panel -> Network Connections -> Right click on your Local Area Connection and select properties -> Click on TCP/IP and select properties. Now insert 192.168.0.1 as the IP address and 255.255.255.0 as Subnet Mask. Leave default gateway blank. Now go back to Control Panel and select Administrative Tools -> Services -> DCHP and select disable DCHP. by grrinder edited by KeysCapt Being able to browse but not download is usually caused by NIC problems. Move your NIC to a different PCI slot. If that doesn't work, take out all unnecessary PCI cards like sound cards and 56k modems, and then try each slot. If it works, then you can add the other devices back until you find the problem. You can move the device causing a conflict to a different slot and that may fix the download problems. Feedback received on this FAQ entry:
by Ranma edited by KeysCapt Try what is called "power-cycling" ...
•Unplug the the modem from the USB slot, and unplug the phone line from the modem. •Wait about 2-5 minutes. •Plug everything back up, and restart your computer. •Reconnect, and everything should run smoothly again. by rutypurock edited by KeysCapt More than likely you have to go to the "forwarding" part of your router setup and forward the corresponding ports. The following three links contain some detailed information about which ports to forward and more. Each link has different, but very helpful information to explain and help guide you through the process. http://www.practicallynetworked.com/sharing/app_port_list.htm#zone http://www.practicallynetworked.com/support/gaming_help.htm http://www.dslreports.com/forum/remark,1202066;root=equip,16;mode=flat by Turin edited by KeysCapt When you connect to some servers, they have to be converted into an IP address in order to connect. A file called HOSTS stores these IP addresses. When the address changes it becomes invalid and you are unable to connect to that website. To fix this: 1. Close all browsers. Go to Start, Find and select Files or Folders. by redxii edited by KeysCapt If you have access to your outside test jack (where the main line from your telco connects to your home line, usually via a standard sized telephone jack), find a long phone cord and run it from your DSL modem to the outside test jack directly. This bypasses all of your internal circuitry. If you were unable to connect before and are still unable to connect, your ISP probably has a problem (perhaps a bridged tap or numerous other line quality destroyers). Call your DSL service provider or phone company and ask them to check. If you were unable to connect before due and are able to connect after doing this, the problem is likely inside your house. Your telco probably offers professional installation of a DSL line splitter, which would eliminate internal problems. (I will post information later about self-installing a separate DSL line on the same phone number). by purplejello edited by mballard Actually, they're not really slowing down. After you click on the download button, the download begins while you're typing in the file name. If you take a while to do that a considerable amount of data will be saved before the download speeds start registering. That's why it seems to be zipping along at first. But, after the buffer has caught up, it will then start showing your true download speed. Speed too, will fluctuate as the servers that you're downloading from get busy, and you'll get speeds going up a little, then down a little. Don't forget, it's important to make sure your computer's optimized for speed. Be sure to check out DSLReports Tweak Tools at /tools for tools to help you tweak your speeds, and be sure to check out the Tweaks forum for more useful information! -- submitted by Santa Fe by KeysCapt This is free advice so please take it if you need it. Often we as customers complain about our service and wonder why no one seems to be doing enough. Have you done enough? We expect our DSL provider to bend over backwards to bring us a better connection when often we have made little or no such effort on or own end. Do you have a POTS splitter? Please keep in mind that the device you plug into your phone jacks all over your house are not POTS "Plain Old Telephone Service" splitters but filters and if you are doing this all of your non DSL lines under your house are counting in your total line length and are robbing you of bandwidth. A POTS splitter goes inside of or next to your SNI/NID which is usually a gray or black box located outside where your phone line comes into your house. On one side of the POTS splitter is DSL and the other side is POTS or voice this keeps the DSL signal from running in all of your other lines under your house which will add to your line length. POTS splitters run from around forty dollars and up and depending on which one you buy and where it may be a module that fits in your SNI/NID or a separate box all together. I recommend getting the module type and personally use the LPF-200 by antec products. You can find some nice examples of how this is done here and for older SNIs here. Be sure to take out that half-ringer since it can add to the length of your line. Do you have a dedicated or "home run" line? Dedicated or "home run" means that the line for your DSL runs from the SNI/NID to the wall jack or interface for your DSL modem and nowhere else and it is best to have no other devices installed on this line. It is also best to use CAT5 "category 5" cable to run your dedicated or "home run" line. You can use any of the four pair to do this and it is often suggested that you use pair number two or the orange and white pair. You can also go the extra mile by running CAT5 from your wall jack or interface to your modem of course you will have to do some trimming "cut some of the other wires back" to allow it to fit into the module plug. Always remember these important rules while routing ANY CAT5 cable: 1. Never stretch your CAT5 cable. 2. Always keep your CAT5 cable at least six inches away from ANY other cables this is VERY important for electrical cables as this will cause more noise on the line. If you are a bad judge of distance a dollar bill is usually six inches. 3. Never un-twist the pair any more than one half of an inch, one quarter of an inch is even better if you can get it connected. The same goes for stripping it including the outside jacket. 4. If you have to cross other cables do so at a ninety degree angle. 5. Never crush or kink your CAT5 cable. This includes stapling your CAT5 cable. Use hangers for such purposes which you can get from radio shack or staple wire ties which you can get almost anywhere. 6. Make sure you don't run your CAT5 into a spike or surge protection device as there are sometimes problems with these like you didn't know your new puppy likes to pee in it. =o) It also should not be needed as SBC should have such protection in your SNI/NID already. Are you sharing your dsl with others in the house? Invest in a DSL gateway or router as ICS, Sygate and other software alternatives just don't do as good of a job and cause you to have to leave a computer on so the other computers can use the connection. If you only have one IP a gateway will do just fine. Make sure that what ever you purchase will support PPPoE "point-to-point protocol over ethernet (RFC 2516)". Most that are made for DSL do but it is always a good ideal to make sure since many of the europe DSL providers use PPTP "point-to-point tunneling protocol (RFC 1171)" or PPPoA "point-to-point protocol over ATM (RFC 2364)". DSL gateways can be purchased for as little as thirty dollars depending on where you shop and how much security you are looking for most of them offer NAT "network address translator (RFC 1631)" protection at the very least and are well worth the investment. Also most of them have a built in DHCP "dynamic host configuration protocol (RFC 2131)" server that makes it easy to use multiple platforms without all of the setup nightmares. Are your settings correct? Your MTU "maximum transmission unit" and RCVWINDOW "receive window" are the most important but you should not ignore the rest. If you are not getting one hundred percent transfer efficiency on the DSL-Reports tweak test it is probably your settings and they offer some helpful advice there. I usually obtain best results with an MTU of 1500 and an RWIN of 65535 but your results may vary depending on your line conditions. The DSL-Reports tweak tester is here Do you have noise on your line? If you have noise on your line it may be RF interference you can find good information on tracking it down here. Remember if you refuse to go the extra mile then you can't expect others to do it either and you will find if you have most of the techs will be able to get to the root of your problem much quicker. Thanks to everyone whose fine post I have used in reference here and DSL-Reports for such a fine resource. I couldn't have done this with out you. Feedback received on this FAQ entry:
by callihn4 edited by KeysCapt If your latency is consistently high, you need to question your provider as to your routing. Many ISPs are not national, but are able to sell DSL nationally. In certain cases, they must route traffic all over the place even if you are trying to use local game servers or sites. In other cases, the ISP has real (and hopefully temporary) routing problems, or a critical failure and they are on backup. Normally network specialists plan for optimal routing, but during fast growth, your ISP may have got into a situation where customers pay penalty in ping time while the ISP figures out how to resolve the problem. The first step in diagnosis of high latency is to figure out the ping time to your default gateway. You may do this by using the Line Quality tool at this site, or by using Visual Route from Datametrics (www.visualroute.com). If your default gateway ping is good, the next step is to get a trace to a server that you believe should be nearby. Ideally, nearby servers are available with a few number of hops and low total latency. What can you do if faced with persistent high latency? Unfortunately, nothing. ISPs are not obliged to operate with any minimum latency guarantees, so vote with your feet. Discussing the problem with as senior a technical support person as you can find may reveal they have expansion plans that will ease the problem in your area. When this is not an outright hardware failure, it is usually a device resource allocation problem. (this advice applies to windows PCs only). Open the control panel and get the System icon open. Look in the device list, and check if there are any devices windows has marked with a red cross or any other type of error symbol. Just because there are not, does NOT mean that there are no conflicts!! This is most important to learn! many devices come with poorly written drivers, which do not accurately reflect the hardware. This can mean that windows "overlaps" the resource use with another device resource map without "realizing" it. Resources are scarce (otherwise they would not be called resources) so usually if windows can make this mistake it will! The end result can be a range of mysterious symptoms: video card corruption, mouse pointer freezes, speaker clicks, keyboard freezes, disks seek and re-seek, and activation of the cdrom causes disk activity. The introduction of DSL to a system often requires the introduction of a new card, either ethernet or a DSL modem card.. and this is a good chance for uncovering device problems. The simplest solution is to remove all the devices from the PC that you can (other modems, sound cards etc), then reboot windows and confirm the problems have gone away. Then add back or enable (in the case of motherboard devices such as USB ports), until the problem comes back. If you can narrow it down to two conflicting cards or devices, refer to websites for updated drivers to see if that fixes them. Frequent loss of line sync (the normally green light on your DSL modem goes out, blinks, turns yellow or red, and the Internet is suddenly unreachable) can be caused by:
If you suspect modem malfunction, check for heat. Replace the modem if you can. If it is an internal modem, change slots and try running with minimum other internal cards. (Remove SCSI cards, Soundblaster cards and so on.) This is to verify that the root cause is not a plain old Windows hardware conflict. If all else fails, it may be a marginal card in the CO DSLAM that is causing your line problems. Suggest (although this might be ignored) that the DSLAM card be re-seated, or that you be swapped to another card. At least one user has reported that not enabling DMA on his hard drive was the cause of his sync problems. by KeysCapt This MIGHT be due to the fact that you entered the information wrong on the application. Check this first. But if you repeatedly get a message saying something like "We are sorry, but our server cannot register you right now, we may be experiencing technical difficutlies, try again later" this could be due to a mis-communication between ASI and SWBell. The first thing i would do is call up ASI and have them register you over the phone. This is fairly simple, and they will give you a temporary password. If they encounter trouble with this, such as they can't find that you are registered to recieve dsl, have the person on the phone contact SWbell and check you account information. If your account information was not processed correctly, you will be unable to register, which could lead to some major headaches. If this still does not work, post your problem in the forum area under "swbell" and you may get a response that helps you out. by Centurion2 Answer 1: First, do you want or need to continue Answer 2: If you want to stick with your current ISP, Broadband - especially DSL - is very complex, and the issues surrounding it are not always understood well by DSL providers. Consequently your ISP's limited and costly support resources are often over-burdened, which can make it very hard for them to respond to you when you really need the help. Many DSL problems can be difficult to correct because there are often at least 3 different companies that have their hands in your DSL connection: Your ISP, Telco, and network provider. Since these companies may not let you communicate with anyone else but the ISP when you have a problem, resolving a problem with your telco or network provider may require a lot of persistence, patience, and hold times with your ISP. Since in the end you may need to call your ISP for help, follow these instructions. Sometimes you'll get through to exactly the right person,
Content-Disposition: form-data; name="previewed" 1 by Southpaw Call your local telco and have them test your phone lines. Even have them come out to your location. It's their job, don't let them tell you otherwise. by pcfit edited by DrTCP Although you may still have an old dialup ISP account with active email address, you may have problems using it from your new DSL line. Some ISPs do not let people send email (a process not normally password authenticated), from outside their network. Others require that you fetch first then you may send. The solution is to forward your old email account to your new DSL ISP email address, and only send email as your new account. When everyone has updated their address books for you, you may deactivate the old email account entirely. Feedback received on this FAQ entry:
by bmorgan42175 Search your registry for TunnelMode, change it to 0. Re-boot, you can now set your mtu above 1454 by sloppyjoe edited by DrTCP Your connection seems to work well, but it takes way too long for your modem to sync with your CO (over 10 minutes, up to hours), such as after power up. Reasons for slow sync with the CO: 1. Telephone surge suppressor in the circuit between the modem and the phone jack, such as those found on a UPS or power strip. 2. No micro filter installed between phones and the telco line. (Applies to splitterless installations.) 3. Poor line quality. 4. Problem with modem in CO. To troubleshoot slow sync, follow these steps: 1. Disconnect all phones and other equipment from your phone jacks. 2. Make sure that the phone line connection to the modem is direct. Do not wire through any surge suppressors. 3. Power up the modem. It should sync with the CO within 5 or 10 minutes. 4. If it still won't sync, call your ISP to report the problem. Your phone line has it's own modem at the CO end. There could be a problem with it. Or there could be a problem with your line. Once your sync time is OK, plug in each of the phones or other equipment one at a time and check modem sync by power cycling your modem. With splitterless setups, make sure there is a micro filter between each phone and the phone jack. by DSL Robot edited by DrTCP Yes, it will. It will act like any other un-filtered device plugged into your telephone line. An exceptionally strong DSL signal will overcome this, but the best bet is to pull (or have pulled) a new wire from your network interface to the DSL jack. And this new wire needs to be unfiltered! by MowerMan5 edited by DrTCP If you are running ADSL (voice over data lines only) and hearing a screeching feedback pulse (sounds like when you pick a phone up while dialed-up), your line needs filters. You should place an ADSL Microfilter on every phone you have at the jack, but not the jack the DSL line is plugged into. Most in-line microfilters can be found at your local computer retail store for under $15. If you have a wall-mounted phone (ie: older rotary phones) you must buy a different type of filter than runs for around $30. In-line filter: Wall mount filter: by Mike edited by KeysCapt If you are able to access almost all web sites but have any or all of the following symptoms your MTU (Maximum Transfer Unit) may be incorrect. Can not access certain web sites or see particular frames within a website. Can not access web sites or sections of web sites that require a username and password (i.e. banking, stock quote, online ordering, etc). Can not access or download from certain FTP sites. Can not access certain servers or information while using a VPN client. Can not access web based email sites or send/receive emails. Can not access POP based email or send/receive emails. Can not send/receive file transfers. To find the correct MTU for your configuration you must run a simple DOS Ping test. Please reference the following steps: The command for this ping test is ping www.dslreports.com -f -l xxxx. •There is a single space between each command. •"-l" is a lower case letter L, not the number one. •The last four numbers are the test packet size. Open a DOS prompt screen by clicking on Start>Programs>MSDOS-PROMPT. You can also use the Run Command by clicking on Start>Run then type in "command" for Windows 95/98/ME or "cmd" for Windows 2000/XP. At the DOS Prompt type in ping www.dslreports.com -f -l 1472 and hit Enter. Notice that the packet needs to be fragmented. (Figure 1) Drop the test packet size down (10 or 12 bytes) and test again. Notice that the packet still needs to be fragmented. (Figure 2) Drop the test packet size down more and test again until your reach a packet size that does not fragment. (Figure 3) Once you have a test packet that is not fragmented increase your packet size in small increments and retest until you find the largest possible packet that doesn't fragment. Take the maximum packet size from the ping test and add 28. You An example: 1440 Max packet size from Ping Test + 28 IP and ICMP headers 1468 Your optimum MTU Setting You can download and use DrTCP or any similar registry editing application to change your MTU. Remember, if you have more than one network adapter on a PC you must change the MTU on the correct network adapter associated with your broadband connection. Additionally, if you have a network with more than one PC, all computers must have the same MTU setting. Note: You must reboot your machine in order for the new MTU settings to take place. An example of changing the MTU using DrTCP is shown below. (Figure 4) © Andy Houtz by Andy Houtz edited by KeysCapt DSL Error Code Identifications Error Messages ------------------------------- 600 An operation is pending. 601 The port handle is invalid. 602 The port is already open. 603 Caller's buffer is too small. 604 Wrong information specified. 605 Cannot set port information. 606 The port is not connected. 607 The event is invalid. 608 The device does not exist. 609 The device type does not exist. 610 The buffer is invalid. 611 The route is not available. 612 The route is not allocated. 613 Invalid compression specified. 614 Out of buffers. 615 The port was not found. 616 An asynchronous request is pending. 617 The port or device is already disconnecting. 618 The port is not open. 619 The port is disconnected. 620 There are no endpoints. 621 Cannot open the phone book file. 622 Cannot load the phone book file. 623 Cannot find the phone book entry. 624 Cannot write the phone book file. 625 Invalid information found in the phone book. 626 Cannot load a string. 627 Cannot find key. 628 The port was disconnected. 629 The port was disconnected by the remote machine. 630 The port was disconnected due to hardware failure. 631 The port was disconnected by the user. 632 The structure size is incorrect. 633 The port is already in use or is not configured for Remote Access dialout. 634 Cannot register your computer on the remote network. 635 Unknown error. 636 The wrong device is attached to the port. 637 The string could not be converted. 638 The request has timed out. 639 No asynchronous net available. 640 A NetBIOS error has occurred. 641 The server cannot allocate NetBIOS resources needed to support the client. 642 One of your NetBIOS names is already registered on the remote network. 643 A network adapter at the server failed. 644 You will not receive network message popups. 645 Internal authentication error. 646 The account is not permitted to log on at this time of day. 647 The account is disabled. 648 The password has expired. 649 The account does not have Remote Access permission. 650 The Remote Access server is not responding. 651 Your modem (or other connecting device) has reported an error. 652 Unrecognized response from the device. 653 A macro required by the device was not found in the device .INF file section. 654 A command or response in the device .INF file section refers to an undefined macro 655 The macro was not found in the device .INF file section. 656 The macro in the device .INF file section contains an undefined macro 657 The device .INF file could not be opened. 658 The device name in the device .INF or media .INI file is too long. 659 The media .INI file refers to an unknown device name. 660 The device .INF file contains no responses for the command. 661 The device .INF file is missing a command. 662 Attempted to set a macro not listed in device .INF file section. 663 The media .INI file refers to an unknown device type. 664 Cannot allocate memory. 665 The port is not configured for Remote Access. 666 Your modem (or other connecting device) is not functioning. 667 Cannot read the media .INI file. 668 The connection dropped. 669 The usage parameter in the media .INI file is invalid. 670 Cannot read the section name from the media .INI file. 671 Cannot read the device type from the media .INI file. 672 Cannot read the device name from the media .INI file. 673 Cannot read the usage from the media .INI file. 674 Cannot read the maximum connection BPS rate from the media .INI file. 675 Cannot read the maximum carrier BPS rate from the media .INI file. 676 The line is busy. 677 A person answered instead of a modem. 678 There is no answer. 679 Cannot detect carrier. 680 There is no dial tone. 681 General error reported by device. 682 ERROR WRITING SECTIONNAME 683 ERROR WRITING DEVICETYPE 684 ERROR WRITING DEVICENAME 685 ERROR WRITING MAXCONNECTBPS 686 ERROR WRITING MAXCARRIERBPS 687 ERROR WRITING USAGE 688 ERROR WRITING DEFAULTOFF 689 ERROR READING DEFAULTOFF 690 ERROR EMPTY INI FILE 691 Access denied because username and/or password is invalid on the domain. 692 Hardware failure in port or attached device. 693 ERROR NOT BINARY MACRO 694 ERROR DCB NOT FOUND 695 ERROR STATE MACHINES NOT STARTED 696 ERROR STATE MACHINES ALREADY STARTED 697 ERROR PARTIAL RESPONSE LOOPING 698 A response keyname in the device .INF file is not in the expected format. 699 The device response caused buffer overflow. 700 The expanded command in the device .INF file is too long. 701 The device moved to a BPS rate not supported by the COM driver. 702 Device response received when none expected. 703 ERROR INTERACTIVE MODE 704 ERROR BAD CALLBACK NUMBER 705 ERROR INVALID AUTH STATE 706 ERROR WRITING INITBPS 707 X.25 diagnostic indication. 708 The account has expired. 709 Error changing password on domain. 710 Serial overrun errors were detected while communicating with your modem. 711 RasMan initialization failure. Check the event log. 712 Biplex port is initializing. Wait a few seconds and redial. 713 No active ISDN lines are available. 714 Not enough ISDN channels are available to make the call. 715 Too many errors occurred because of poor phone line quality. 716 The Remote Access IP configuration is unusable. 717 No IP addresses are available in the static pool of Remote Access IP addresses. 718 PPP timeout. 719 PPP terminated by remote machine. 720 No PPP control protocols configured. 721 Remote PPP peer is not responding. 722 The PPP packet is invalid. 723 The phone number, including prefix and suffix, is too long. 724 The IPX protocol cannot dial-out on the port because the computer is an IPX router. 725 The IPX protocol cannot dial-in on the port because the IPX router is not installed.. 726 The IPX protocol cannot be used for dial-out on more than one port at a time. 727 Cannot access TCPCFG.DLL. 728 Cannot find an IP adapter bound to Remote Access. 729 SLIP cannot be used unless the IP protocol is installed. 730 Computer registration is not complete. 731 The protocol is not configured. 732 The PPP negotiation is not converging. 733 The PPP control protocol for this network protocol is not available on the server. 734 The PPP link control protocol terminated.. 735 The requested address was rejected by the server.. 736 The remote computer terminated the control protocol. 737 Loopback detected.. 738 The server did not assign an address. 739 The remote server cannot use the Windows NT encrypted password. 740 The TAPI devices configured for Remote Access failed to initialize or were not installed correctly. 741 The local computer does not support encryption. 742 The remote server does not support encryption. 743 The remote server requires encryption. 744 Cannot use the IPX net number assigned by the remote server. Check the event log. 752 A syntax error was encountered while processing a script. 769 : The specific destination is not reachable. (According to Microsoft this behavior may occur if the network card in your computer is not turned on [enabled].) by teh edited by KeysCapt How do I change the DNS server address(es) in Windows 95, 98, or ME?
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by MacGyver edited by KeysCapt Also read About DSL for lots more information |