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Intermittant Disconnects - Cable Modem Timeouts

Regular Visitor

Intermittant Disconnects - Cable Modem Timeouts

Hi,

 

Recently I've been receiving several short internet disconnects daily.   Looking at the event logs of my Netgear CM1000, it shows critical T2/T3 timeouts exactly at the times when I lose the connection.  I also am seeing a lot of uncorrectable codewords. 

 

I've called into support, and was essentially told I would have to get them on the phone to run a diagnostic when the issue was occurring.  Of course, this is imposssible because the outages only last 1-2 minutes and it takes longer than that to reach someone.  I've done the basic troubleshooting of several equipment refreshes and even hard-wiring my PC to my cable modem to eliminate my router as the source of the problem.

 

I see similar issues to mine in this forum, so I'm hoping someone is able to help.

 

In case my screenshot attachments are blocked, I've also posted them here: https://imgur.com/a/5hTUFCw

 

Thank You!

 

cable-modem-channels.JPGcable-modem-error-log.JPG

Expert

Re: Intermittant Disconnects - Cable Modem Timeouts

Can't see your pics. Since you are a new poster, they likely need to be approved by a Forum Admin. Or you may need to make a minimum number of posts.

You could try hosting them at one of those free third-party pic hosting sites and post the link to them here.



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Regular Visitor

Re: Intermittant Disconnects - Cable Modem Timeouts

I have a 3rd party image link in the original message

https://imgur.com/a/5hTUFCw

Expert

Re: Intermittant Disconnects - Cable Modem Timeouts

O-k I see it now. The SNR's on the downstream channels are terrible / out of spec. Seems that there is noise ingress in to your line(s) somewhere. That can cause random disconnects, spontaneous re-booting of the modem, and speed and latency problems.

In a self troubleshooting effort to try to obtain better connectivity, check to see if there are there any excess/unneeded coax cable splitters in the line leading to the modem that can be eliminated/re-configured. Any splitters that remain should be high quality and cable rated for 5-1002 MHz, bi-directional, and no gold colored garbage types like GE, RadioShack, RCA, Philips, Leviton, Magnavox, and Rocketfish from big box stores like Home Depot, Lowes, Target, Wal-Mart etc. Splitters should be swapped with known to be good / new ones to test

If there aren't any unneeded splitters that can be eliminated and if your coax wiring setup can't be reconfigured so that there is a single two way splitter connected directly off of the drop from the street/pole with one port feeding the modem and the other port feeding the rest of the house/equipment with additional splits as needed, and you've checked all the wiring and fittings for integrity and tightness and refresh them by taking them apart then check for and clean off any corrosion / oxidation on the center wire and put them back together again, then perhaps it's best to book a tech visit to investigate and correct. The problem may lie beyond your premises in the neighborhood plant / lines somewhere.



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We ask that you post publicly so people with similar questions may benefit from the conversation.
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Regular Visitor

Re: Intermittant Disconnects - Cable Modem Timeouts

Thank you for your reply, I appreciate it.

 

I was able to get a Comcast tech out to my house today.  He hooked up a device to the same wall jack my modem is plugged into and said he couldn't see any issues.  I even showed him the 50K uncorrectable codewords which logged at the modem for each downstream channel after we plugged it back in as well as some downstream channels which were reading below 30 dB SNR.

 

There is only 1 splitter in the house which Comcast installed a few years ago.  Not sure what to do next.

 

Expert

Re: Intermittant Disconnects - Cable Modem Timeouts

I can't believe that it was left like that........ If you continue to have problems, call in and complain again ! Get the techs re-involved until it is fixed properly. Good luck with it !!



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We ask that you post publicly so people with similar questions may benefit from the conversation.
Was your question answered? Mark the post as Best Answer!