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KitFox

join:2002-10-09
Denver, CO
kudos:1
reply to fatmanskinny

Re: [Connectivity] Purchase your own modem = Comcast interfering

The custom firmware on the routers will probably have the SPI (Stateful Packet Inspection) firewall activated by default. It allows things like Javascript and specific web sites and such to be blocked. Unfortunately it also demolishes the CPU of all but the most hardy of routers. I have a router with a very hefty CPU. Routing gigabit internally is a fraction of a percent of the CPU normally. The firewall spikes the CPU and network handling and reduces the usable bandwidth tremendously.

Try turning off the firewall feature of the router and see if that helps.

MisterP

join:2012-10-11
US
reply to fatmanskinny
OR, you could get a 5341J Zoom modem, better modem (CableLabs said so, so ), better warranty, 8 channel down for 70 bucks and stick it to The Man/The System (The Motorola man that is)

Come to the dark side lol

This comes from a former 6121 owner who got fed up with the T3s and etc issues and was especially glad I switched when Motorola's firmware "solution" to the T3/T4 issue was not to actually address/resolve it, but just to lock out the offending channel, thus dropping you to two upstreams. Hooray for complacency and band-aids.


fatmanskinny
Premium
join:2004-01-04
Wandering
Reviews:
·Vonage
·Comcast Digital ..
reply to YukonHawk
Ha. I left Comcast Xfinity Voice for Vonage. $9.99 a month + taxes. I don't even use my home phone that much to justify $47+ a month for Comcast Phone.
--
A citizen of The United States of Amnesia. How quickly we forget.


YukonHawk

join:2001-01-07
Patterson, NY
Reviews:
·Comcast
reply to fatmanskinny
So I called Comcast over the weekend to see if I could purchase my own modem...they said sure! But then I felt the vice tighten around my plums when the rep said," You will then need to pay a monthly charge for the EMTA" that we get for free now for the VoIP. I said thanks but no thanks and hung up! Ya can't win!!!
(I have a Cisco 3008 for the internet and an Arris EMTA for the VoIP)


fatmanskinny
Premium
join:2004-01-04
Wandering
Reviews:
·Vonage
·Comcast Digital ..

3 edits
reply to IowaCowboy
Thanks. I just headed to Best Buy and picked one up. In addition to updating the firmware on my routers and killing the DHCP server in my Vonage box (it sits behind the router, not before it), I will have Comcast add the new modem later today and see what happens.

I will return the 6121 back. Thanks again.

EDIT: So I connected the 6141 and seem to be rocking and rolling. However, I discovered another issue. I am using 2 Linksys 54GLs with open source software. They have 10/100 port connections. When I connected my modem directly to my laptop, it switched to 1000 throughput.

The bottleneck is in the routers. I have to get a newer router in the near future as I am losing about 300% of my available download bandwidth when connecting through the Linksys routers. I pull 35/6 directly connected to the modem and 7-8/5 through the routers.

I will probably keep the Linksys as a separate wireless LAN for visitors and work-related projects and use the new wireless LAN for personal surfing and my Vonage service.

Thanks everyone for your assistance.

--
A citizen of The United States of Amnesia. How quickly we forget.

andyross
Premium,MVM
join:2003-05-04
Schaumburg, IL
reply to IowaCowboy
The 6180 has been out for a long time and was one of the first 8x4 modems, but I'm not certain if Comcast ever supported it.


IowaCowboy
Iowa native
Premium
join:2010-10-16
Springfield, MA
kudos:1
Reviews:
·Verizon Broadban..
·Comcast

2 edits
reply to fatmanskinny
I was at Best Buy today and they now have the Motorola 6141 for the same price they were selling the 6121 for (currently $99.99 at the Holyoke Mall BB).

I would return the 6121 and get the 6141 as that supports 8x4 channel bonding.

The Best Buy 6141 comes in a white case but with the same design as the 6121 (except the case is white instead of black).

Edit: I also found out that there is now the 6180, which is also 8x4 channel bonding.


fatmanskinny
Premium
join:2004-01-04
Wandering
Reviews:
·Vonage
·Comcast Digital ..

2 edits
reply to andyross
I am starting to wonder if my routers may be involved. I have two Linksys 54 routers with Tomato running on them and they have 192.168.1.1 and 192.168.2.1 addresses. They are both linked together where the 192.168.2.1 router is wirelessly bridged into the other one.

I was surfing again this AM and the connection locked up. Speeds tests through Chrome came back really low (700k/300k). When I tried to hit the modem, I couldn't reach the page to refresh it. When I tried to hit my routers, they were taking a long time to come up and display. I would think since my wireless routers sit behind my modem, I would be able to hit them regardless of what's going on with Comcast's network. However, I couldn't hit them for some seconds if not about a minute.

I have some more troubleshooting to do and may need to completely dismantle my network and rebuild piece by piece with testing each time for a few days. It can also be the laptop, which is relatively new. I just noticed the firmware for my routers are 3 versions out of date (1.25). I am going to start there.

Any other ideas appreciated.
--
A citizen of The United States of Amnesia. How quickly we forget.

andyross
Premium,MVM
join:2003-05-04
Schaumburg, IL
reply to fatmanskinny
The T4 Timeout issue with the middle channel is a known bug with the Motorola's. It's online, but the status page has that odd Offline message. Personally, I found that doing a power-off reboot seemed to clear up a T4 more reliably than rebooting from the GUI.


NetFixer
Bah Humbug
Premium
join:2004-06-24
The Boro
Reviews:
·Cingular Wireless
·Comcast Business..
·Vonage
reply to fatmanskinny
said by fatmanskinny:

Funny thing is I just rebooted the modem through the GUI interface and that T4 Timeout error disappeared and the modem is showing as being Operational instead of Offline.

I will continue to monitor it.

That screen that shows the modem as Offline with failed tests seems to be a firmware bug in the SB6121 that sometimes happens when there are problems with getting the upstream bonded channels fast enough to satisfy its timeout algorithms; and a software reboot usually makes it go away.

The couple of times I have seen that, the modem was actually on-line; it was just the display page that had not been updated properly.

FWIW, my SB6121 has been on-line for a month with no problems since the last reboot, and the only times it has ever disconnected was because of Comcast problems, or because I was shuffling equipment around and had to unplug it. Of course, lemons do get out the factory door, so YMMV.
--
A well-regulated militia, being necessary to the security of a free State, the right of the people to keep and bear arms shall not be infringed.

When governments fear people, there is liberty. When the people fear the government, there is tyranny.


fatmanskinny
Premium
join:2004-01-04
Wandering
reply to Brendan
Lol! I left myself wide open for that picture.


fatmanskinny
Premium
join:2004-01-04
Wandering
Reviews:
·Vonage
·Comcast Digital ..
reply to NetFixer
Funny thing is I just rebooted the modem through the GUI interface and that T4 Timeout error disappeared and the modem is showing as being Operational instead of Offline.

I will continue to monitor it.
--
A citizen of The United States of Amnesia. How quickly we forget.


NetFixer
Bah Humbug
Premium
join:2004-06-24
The Boro
Reviews:
·Cingular Wireless
·Comcast Business..
·Vonage
reply to fatmanskinny
said by fatmanskinny:

The firmware is SB_KOMODO-1.0.6.8-SCM01-NOSH.

That is the latest firmware, so at this point, hopefully your replacement rental modem will arrive soon and you can then find out if the T4 timeouts are because of a defective SB6121, or because of problems in Comcast's infrastructure.
--
A well-regulated militia, being necessary to the security of a free State, the right of the people to keep and bear arms shall not be infringed.

When governments fear people, there is liberty. When the people fear the government, there is tyranny.


fatmanskinny
Premium
join:2004-01-04
Wandering
reply to NetFixer
The firmware is SB_KOMODO-1.0.6.8-SCM01-NOSH.


NetFixer
Bah Humbug
Premium
join:2004-06-24
The Boro
Reviews:
·Cingular Wireless
·Comcast Business..
·Vonage
reply to fatmanskinny
Those T4 Timeouts are the problem, but with your signal levels, that should not be happening. Either that specific modem really is defective, or Comcast is having some infrastructure problems. If you look at the Help tab in the modem, what firmware version is installed?

If you have already told Comcast to send you another rental modem, you can check its signal levels and see what it does when it arrives. Personally, I would hold on to the SB6121 until I was sure that the problem was actually the modem (but you don't want to keep it so long that the retailer won't take it back).
--
A well-regulated militia, being necessary to the security of a free State, the right of the people to keep and bear arms shall not be infringed.

When governments fear people, there is liberty. When the people fear the government, there is tyranny.


fatmanskinny
Premium
join:2004-01-04
Wandering

1 edit
reply to NetFixer
Nevermind on this post. See above!


fatmanskinny
Premium
join:2004-01-04
Wandering
Reviews:
·Vonage
·Comcast Digital ..

1 edit
reply to NetFixer
Click for full size
Status_Tab
Click for full size
Signal_Tab
Status and Signal images attached.


Brendan
Warr Guitar is here

join:2000-07-14
Littleton, CO
reply to fatmanskinny

It's a Conspiracy!
I have an SB6120, working flawlessly, since I returned the "ordained" modem. This is in Denver, CO.


fatmanskinny
Premium
join:2004-01-04
Wandering
reply to NetFixer
Nah. I already ordered a new modem from Comcast. I'll consider the $7 rental free as insurance and return the POS Motorola modem.
--
A citizen of The United States of Amnesia. How quickly we forget.


fatmanskinny
Premium
join:2004-01-04
Wandering
Reviews:
·Vonage
·Comcast Digital ..
reply to pflog
Yeah, I have to give them the benefit of the doubt. For $7 a month, at least I have the peace of mind that if the modem craps out, I can have them replace it. Since I work from home at times and need to have pretty solid speeds, I can't risk using this modem after today.
--
A citizen of The United States of Amnesia. How quickly we forget.


NetFixer
Bah Humbug
Premium
join:2004-06-24
The Boro
Reviews:
·Cingular Wireless
·Comcast Business..
·Vonage
reply to fatmanskinny
said by fatmanskinny:

I purchased a new Motorola SB 6121 modem from Walmart and returned Comcast's Voice Modem as I moved to Vonage. I have been having intermittent speed issues throughout the day.

Now, after I called Comcast to send me a new Comcast "ordained" modem because I plan to return this modem to Walmart, the speeds on this modem return back to super fast. Are there any known cases of Comcast jacking with your service, forcing you to switch over? Before this voice modem, I had a Linksys that I purchased and suddenly, the Linksys modem would not connect and Comcast could not see it.

In Comcast's defense, I did Google around about the Motorola SB 6121 and have noticed others having similar issues with other cable providers and Comcast but not everyone was having issues.

Any thoughts?

I swapped my rented SMD3G for an SB6121 that I purchased, and I have had no problems with it whatsoever. SB612x modems before firmware release SB_KOMODO-1.0.6.8-SCM01-NOSH did have problems with rebooting if they lost an upstream channel, but that should no longer be a problem.

The SB612z modems are a bit sensitive about their upstream power levels (they need to be below 50dBmv) and that did make them somewhat unreliable prior to the current firmware release (which Comcast should upload automatically). If you are looking for help (and not just ranting), post some screen shots of your modem's Status and Signal tabs.
--
A well-regulated militia, being necessary to the security of a free State, the right of the people to keep and bear arms shall not be infringed.

When governments fear people, there is liberty. When the people fear the government, there is tyranny.


pflog
Bueller? Bueller?
Premium,MVM
join:2001-09-01
El Dorado Hills, CA
kudos:3
reply to fatmanskinny
No way would they do that. It'd come back to bite them big time. I'm 99.99999999% sure this was a coincidence.
--
"I drank what?" -Socrates


fatmanskinny
Premium
join:2004-01-04
Wandering
Reviews:
·Vonage
·Comcast Digital ..

[Connectivity] Purchase your own modem = Comcast interfering wit

I purchased a new Motorola SB 6121 modem from Walmart and returned Comcast's Voice Modem as I moved to Vonage. I have been having intermittent speed issues throughout the day.

Now, after I called Comcast to send me a new Comcast "ordained" modem because I plan to return this modem to Walmart, the speeds on this modem return back to super fast. Are there any known cases of Comcast jacking with your service, forcing you to switch over? Before this voice modem, I had a Linksys that I purchased and suddenly, the Linksys modem would not connect and Comcast could not see it.

In Comcast's defense, I did Google around about the Motorola SB 6121 and have noticed others having similar issues with other cable providers and Comcast but not everyone was having issues.

Any thoughts?
--
A citizen of The United States of Amnesia. How quickly we forget.