Home Networking / Router / & WiFi Gateway Help

[akabanrtosh]

I bought this gateway (modem and router in one) when I switched to Comcast from DSL and it worked fine for about 4 months. Four months back I got cable TV too and they put a splitter to the cablebox and since then I have been having problems with my modem rebooting itself several times a day.

I went on several forums and learned that :

I) Spiltter could be the cause

ii) Signal levels could be out of whack

I disconnected the cable TV box (to get rid othe splitter) and things did not improve.

I had Comcast rep come in and he checked out the signal levels and said that they were within limits and that the Gateway was the problem. Signal levels were on that day :

SNR 37.3 dB

Upstream Power 41.7 dBmv

Downstream Power 7.9 dBmv

I contacted Motorola and they say that even though the Downstream Power is within their specs (-15 dBmV to +15 dBmV), any time it is out of -5 dBmV to +5 dBmV range, it is a poor signal and that could cause problems. They also said that this being a DOCSIS 2.0 compliant modem, it is more sensitive to signal fluctutations. They asked me to contact Comcast again.

I have seen on other forums that this is definitely a Comcast problem and they should fix it. I would like to know if anyone is in a similar situation.

Any help/advice on what to do (apart from junking the modem - I spent $100 bucks on it) is welcome.

[akabanrtosh]

One more thing. Just before it reboots I get the following messages in the Event Log:

Fri Feb 17 15:57:19 2012    Critical (3)  Received Response to Broadcast Maintenance Request, But no Un...  
 Fri Feb 17 15:56:46 2012   Critical (3)  UCD invalid or channel unusable   

I have a Comcast tech coming out on Feb 19. Any info I can get on this would be useful.

[i-am-nerdburg]

It's most likely a firmware problem since it appeared about the same time other moto gateways started to have problems (see http://forums.comcast.com/t5/Connectivity-and-Modem-Help/Intermittent-drops-Motorola-sbg6580/td-p/11... I don't know if there is solution other than waiting for Comcast to fix it or replacing the modem.

[Baric]

The SBG901 is marginal at best.  Personally, I would get rid of it.  I know you said you don't want to hear that but short of the Comcast tech getting your signal as close to 0dBmV as possible, it's your best option, and even then it might not clear up your problem.   As pointed out by Motorola, this is a DOCSIS2 device, which is behind the times, I recommend you step up to a DOCSIS3 modem, such as the Motorola SB6120 or SB6121, or perhaps the Zoom 5341J.  Then get a decent wireless router, maybe a Linksys E3200 or Netgear WNDR4000, or whatever suits your needs.  And never get a combo gateweay again, they are nothing but trouble.

[akabanrtosh]

Update

I had Comcast reps come down yesterday (they were supposed to come in on Sunday, but were a no show) and they found problems in the cable connection from the junction box outside coming in to my house. They fixed that and immediately the downstream levels got much lower (now they are around 2.9 dBmV). However, my modem continues to reboot. I definitely think it is a problem with the modem.

However, Motoroal will send me only a replacement (after I send in my modem), So, I guess I am stuck. 

Baric, 

You say that combo gateways are nothing but trouble. Why is that? I have ised combo DSL gateways before and they worked OK. Is this just your experience or there any technical reasons behind this?

Appreciate all of your replies. Thanks

[EG]

My $.02; Combo gateway devices are always a compromise in both quality and performance compared to separate units. In addition, only the ISP can update the firmware so you are always a prisoner of them. Also the firmware is typically crippled by the ISP's customizing of it and they typically eliminate valuable features. One of the biggest issues with gateways is that it is far more difficult to diagnose connectivity issues when it comes to troubleshooting. You can't narrow things down using the process of elimination by removing just the router from the path. I think that CC made a big mistake when they changed their policy and decided to start supplying them instead of dedicated devices. The suits seem to think that this will save them money for support costs but I think that they are getting far more support calls/complaints than ever... We certainly are seeing far more complaints in forums now !

[akabanrtosh]

Thanks

I am going to bite the bullet and for a new cable modem and wireless router. Any suggestions?

[Baric]

---

EG wrote:

My $.02; Combo gateway devices are always a compromise in both quality and performance compared to separate units. In addition, only the ISP can update the firmware so you are always a prisoner of them. Also the firmware is typically crippled by the ISP's customizing of it and they typically eliminate valuable features. One of the biggest issues with gateways is that it is far more difficult to diagnose connectivity issues when it comes to troubleshooting. You can't narrow things down using the process of elimination by removing just the router from the path. I think that CC made a big mistake when they changed their policy and decided to start supplying them instead of dedicated devices. The suits seem to think that this will save them money for support costs but I think that they are getting far more support calls/complaints than ever... We certainly are seeing far more complaints in forums now !

---

 

Yeah, what he said...

[akabanrtosh]

Thanks for all of your replies.

Before I go out and buy a new modem and router, I wanted proof that Comcast connection is OK. So I am planning to rent a Comcast provided gateway for a couple of months.

I also read in other forums that SBG6580 had similar issues and that Comcast provided firmware updates which fixed the problem. When I contacted Comcast to see if there are going to be any firmware update to SBG901, they said that they do not provide firmware updates and directed me to Motorola. Motorola website clearly states that this is the responsibility of the cable company.

I have filed an informal complaint with the FCC. Let's see how it goes.

[akabanrtosh · Accepted solution]

One more update. Read in a different forum that disablingbIP Flood detection and Firewall protection in the Wireless configuration fixes the problems with SBG901. I made this change and rebooted last night at 11 PM and so far so good! Will keep this forum updated.

[Baric]

The fact that you need to do this to get it to work is an indication of the problems this gateway has.  Get rid of it.  But thanks for posting the work around, it might help others with a similar issue.

[akabanrtosh]

That did not help either. My gateway continues to reset. I am going rental. Comcast is coming tomorrow to install their modem. Let's see how it goes.

[Baric]

If you buy your own cable modem, you will save the $7/mo rental fee.  As long as you don't have Xfinity Voice, buying your own cable modem makes a great deal of sense, both financially and practically.

[akabanrtosh]

I will do that eventually. I want to be satisfied that Comcast service is OK with their modem before I buy my own. 

[akabanrtosh]

Comcast techs came and installed a ubee modem and Netgear router. I do no t see any reboots on the modem, but there are intermittent outages in my connectivity to the Internet.

However, I do not see anything in the EVENT LOG page of the modem. Looks like all that the new modem does it to mask the symptoms of the problem the connectivity which SBG901 gateway was exihibiting by rebooting itself. I am going to complain to Comcast again, but doubt that I would get very far with them sinc ethe modem does not disconnect anymore. Will keep you posted on the outcome.

[Baric]

What are the signal levels reported by the modem? If hte modem is not dropping the signal, maybe it's the Netgear router, what model is it?  I highly recommend ONLY using your own decent router, the el cheapo ones used by Comcast are nothing to write home about.

[akabanrtosh]

Downstram 5.9 dBmV SNR 39 DB Upstream 43 dBmV

[Baric]

Those numbers look good, as long as they don't flucuate much.  There are a few values only Comcast can see the upstream receive power and the upstream SNR, you have to call them to get those.

[akabanrtosh]

I have not updated this forum for a while. Since I did not very far with either Motorola or Comcast I complained to he FCC and that got Comcast moving. Comcast and Motorola which had been denying that they were responsible for any firmware updates are now working together to reproduce my problem and find a fix. I have received several calls from Comcast corporate office with follow up calls from their Technical manager on the disposition of my complaint. They do not have a resolution yet, but am told that Motorola has reproduced the problem and is working on a fix which is likely by early June. In the meanwhile Comcast said that they would try to provide me with a temp fix. I am waiting now to see how it turns out.

[MichaelNguyen23]

The SAME exact thing is happening to me. Please let me know what happens with comcast.

[djohnbosko]

I am facing the same issue for last couple weeks and doing circus with Comcat and Motorola

[MajicMike]

I have the same problem and am getting the run around.  Motorola threatened to void my warrantee if I tried to find software to query the modem data on a regular basis.  They called it hacking.  Comcast just checks signal and tells me it is OK, check with Motorola.  Motorola says replace the modem, which I purchased independently, and will not, after I asked several times, tell me why I should.  I think they are working together against us.  I tried to set up a support account at Motorola and was told it was only for cable companies and their installers.  What's up with that?

Did you get any resolution after calling the FCC?  As far as I can tell they are not posting solutions here.

[Baric]

Gateways are problems, always have been, always will be.  Stop fighting to make junk work and get a real cable modem (Motorola SB6120/6121 or Zoom 5431J) and a decent wireless router and start enjoying your high speed Internet connection as opposed to having nothing but problems.

[acparker]

I have been having similar problems.  I was hoping that a fix would be forthcoming in June.  I will be getting a 7-day loaner from Comcast this week.

I have had a conversation with Motorola and they say that, from my description of the modem's behavior, it is a signal issue.  I just double checked compatibility with Comcast and the SBG901 is still listed as approved for my service speed, and is not end-of-life equipment.  (Ironically, while setting up Chat with Comcast customer service, the modem rebooted and I lost the session.)

They charged me $50 the last time the tech came by and found nothing apparently wrong.  I have protested the charge.  I don't know how they can diagnose an intermitent loss of service by hanging a signal logger on the cable for one minute.  In any case, if it is a software issue, it is still their problem.

[jerrytaylor501]

this rebooting issue  is not the modem's fault, it is merely doing what it is told to do .  look at the sites you are going to . If it is a site that comcast doesnt perticurly like, such as adult sites or intereactive adult sites such as IMVU.  It is their way of disconnecting you  from them .  dont take my word for it. run a test! contact norton through a live chat , let them connect to your machine, then run the site you usually run when the modem resets .  between Norton and Comcast , the issue was fixed. but what they did,is a 64 million dollar question .  Allowing the firewall to let what ever site it is that makes the modem jump, allow all of it  through the modem software.  And every once in a while , check the modem log.  who's ever fault it is , i am not sure, but it aint the modem , the modem is simply doing what it is told to do .

[sillylove]

Worked !!! thanks.

[sillylove]

akabanrtosh solution worked for me!

Thank you !

* No Guts No Glory !