Connection dropouts, T4 timeouts. & just one upstream channel

Have you tried power cycling the modem ?

Yes, sorry, I should have mentioned:  I've power cycled the modem 4 or 5 times since the problem first appeared, but I didn't look at the signal status and event log info until after the two most recent power cycle attempts.  My posted info is from 21 hours of uptime.  

I also tried the Xfinity online connection testing tool, but that appeared to be mostly just another power cycle (?). 

     Dave

O/K try resetting it back to factory defaults by depressing and holding in the recessed reset button on the rear for 30 seconds.

OK, I pressed the modem's recessed reset button on back panel for 30sec.

Looks like the issue persists -- here is modem status and event log info after 1hr 40min uptime, following SB6190 factory reset step:

Modem status:  https://imgur.com/a/SAFmfFS

Modem event log:  https://imgur.com/a/Kic1TiM

Thanks,

    Dave

So it could be 4 things. Either they may have taken the other upstream channels down deliberately due to some sort of maintenance / system upgrades, or there is noise ingress present in the return path that is causing the unbonding of the channels, or the modem is malfunctioning, or they put a filter on your line.

So even though the signal stats looked o/k at those snapshots in time, the error log entries confirm that something is going on. Perhaps there is indeed noise ingress into the line(s) somewhere.

There are other signal stat figures that can't be read by the modem. They are the "Upstream Rx Power" (Upstream Receive Power Level), the "Upstream SNR Ch." (Upstream Signal To Noise Ratio), and the "Upstream ICFR" (In Channel Frequency Response). These are as equally important in diagnosing connectivity issues as are the modem's stats.

I'm going to escalate your issue to the Comcast corporate employees that are available to these boards. They can check the CMTS (Cable Modem Termination System) for any real time degradation and / or error reports, see your node / cable plant and modem health, and see whether or not everything is in the green zone. They can also see a history plot for the modem and poll for those upstream receive signal stats.

You should get a reply here in your topic. Good luck !

Thanks, EG!  I'll hang on for a Comcast employee to reach out next.

If it comes down to a modem malfunction, I have a brand new CM1200 (unopened).  I'd probably want to upgrade from my (previously rock solid) SB6190 to the CM1200 soon in any case, but I thought it might make more sense to troubleshoot the current, relatively new issue first (assuming the modem isn't failing....).

     Dave 

Hi there, DesertRules. We appreciate you coming here for support. We understand internet connectivity issues can be super frustrating and we would like to help. We can take a look at some diagnostic reports on this end to see if we can help narrow down the cause. If you can start by sending us a private message with your name (first and last) we can continue from there.

To send a private message, please click our name "Comcast_Support" then select "Send a Message" on the right side.

We look forward to working with you. 

EG and all,

Comcast_Support and I are PM'ing -- will update the community here shortly to share what happens next.  So far, Comcast_Support says my signal levels look low from their end.  Root cause not yet determined.  May require a Comcast technician visit to my house.

More soon.....

     Dave

All,

Issue still not resolved -- Just sharing the latest from my Comcast_Support PM exchanges, keeping others informed just in case the info is helpful:

     Dave

-----------------------------

:

Hi again,

I do need a Comcast technician visit, per my last PM with answers to questions "which days are best" and "contact number". 

Can you schedule it, or should I call Comcast customer support via phone to set it up?  

I've tried the following additional measures, with no improvements:

1) Changed from SB6190 modem to brand new CM1200 modem -- still only one upstream channel, and lots of uncorrectable errors on downstream channels - same as before.

2) Changed out the ground block connector in my outside junction box, and cleaned up the ground connection.  No improvements.

Thanks,

     Dave

Good luck with it !

Updates:  

Comcast's technician was friendly and efficient yesterday afternoon.  He said apparently my line had a filter installed by a previous Comcast technician, probably because of measured noise being injected from my house back into the Comcast system.  He said the technician should have left me a door hanger note (I didn't get one).  This is very consistent with my observation that my internet relibaility issues started right after two Comcast trucks weere in our area about 4 weeks ago and technicians did some work, including within the green metal drop box in my front yard. 

Anyway, my technician installed a higher-quality coax cable in my house between wall connector and modem (replaced the one I've been using for over 10 years), and he removed the filter from the cable drop box outside and tightened things up.  

I'm now seeing no more modem log events, and I am back to having four upstream channels instead of just one (was due to the recently installed filter).  My connection appears to have stopped dropping out intermittently, but that's with my new modem (Netgear CM1200) which was acting more resilient to this issue than was my Arris SB6190 prior to the technician visit. 

I am still seeing lots of correctable AND uncorrectable errors on my downstream channels (see below, 24 hours uptime).  But perhaps I won't worry about this unless we encounter user-visible problems like intermittent dropouts -- in that case I'd open a new forum thread & another service request to Comcast.

Thanks!

      Dave

Please also post what the upstream channels look like now.

Hey I see you expanded your original "3 things" list from 10/22 to "4 things" to include the filter scenario -- I figured you were already technically correct on noise ingress & I guess it was a combination, one led to the other. 

In my case, I do wish Comcast had said "hey, we saw injected noise from you, so we slapped a filter on your line - let us know if you have any problems.....".

Thanks for your help with this, EG!

      Dave

Sure!  Here is the upstream channels info, and the rest below that: