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intermittent outages, slow upload speed, normal download speed

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intermittent outages, slow upload speed, normal download speed

I have a very simple setup: cable from wall into modem/router, cable from modem to computer. This is upstairs. There's also a TV downstairs with its own cable connection to the wall. Intermittently the modem drops the signal and goes off, reboots, sometimes repeatedly. Disconnecting power and waiting sometimes helps. Then a day may pass with no problem. When there's a problem, but it's still working, speed shows normal download, slow upload, sometimes very slow (0.8 instead of normal 5 or 6). What to try?

Expert

Re: intermittent outages, slow upload speed, normal download speed

What do the modem's signal stats look like ? Try getting them here http://192.168.100.1 or here http://10.0.0.1

Please post the *Downstream Power Level*, the *Upstream Power Level*, and the *SNR* (Signal to Noise Ratio) numbers.

What is the exact make and model number of the modem ?




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New Poster

Re: intermittent outages, slow upload speed, normal download speed

Motorola MG7550 cable modem + AC1900 router, 1 year old

 

Downstream

Power level:  All channels are between 1.4 and 2.7

SNR:  One channel is 35.4, all the others are between 39.1 and 39.8

 

Upstream power level

3 channels are “locked”, with levels 38.5, 38.5, 38.0; one is “not locked”, with level 0.0

Expert

Re: intermittent outages, slow upload speed, normal download speed

Please also post the modem's error / event log entries.



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New Poster

Re: intermittent outages, slow upload speed, normal download speed

Here's the event log. Sorry if the formatting isn't good.

 

Event Log

   Log                          

 

 Time    Priority            Description

 Thu Mar 28 01:20:13 2019     Critical (3)        SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=00:40:36:50:78:1e;CMTS-MAC=00:01:5c:6b:de:50;CM-QOS=1.1;CM-VER=3.0;

 Thu Mar 28 01:22:40 2019     Critical (3)        SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=00:40:36:50:78:1e;CMTS-MAC=00:01:5c:6b:de:50;CM-QOS=1.1;CM-VER=3.0;

 Thu Mar 28 01:24:17 2019     Critical (3)        Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=00:40:36:50:78:1e;CMTS-MAC=00:01:5c:6b:de:50;CM-QOS=1.1;CM-VER=3.0;

 Fri Mar 29 17:15:59 2019       Critical (3)        Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=00:40:36:50:78:1e;CMTS-MAC=00:01:5c:6b:de:50;CM-QOS=1.1;CM-VER=3.0;

 Mon Apr 01 08:23:07 2019     Critical (3)        Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=00:40:36:50:78:1e;CMTS-MAC=00:01:5c:6b:de:50;CM-QOS=1.1;CM-VER=3.0;

 Time Not Established              Critical (3)        No Ranging Response received - T3 time-out;CM-MAC=00:40:36:50:78:1e;CMTS-MAC=00:01:5c:6b:de:50;CM-QOS=1.0;CM-VER=3.0;

 Tue Apr 02 18:11:16 2019      Critical (3)        Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=00:40:36:50:78:1e;CMTS-MAC=00:01:5c:6b:de:50;CM-QOS=1.1;CM-VER=3.0;

 Time Not Established              Critical (3)        No Ranging Response received - T3 time-out;CM-MAC=00:40:36:50:78:1e;CMTS-MAC=00:01:5c:6b:de:50;CM-QOS=1.0;CM-VER=3.0;

 Sat Apr 13 06:00:36 2019       Critical (3)        Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=00:40:36:50:78:1e;CMTS-MAC=00:01:5c:6b:de:50;CM-QOS=1.1;CM-VER=3.0;

 Mon Apr 15 08:51:59 2019     Critical (3)        Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=00:40:36:50:78:1e;CMTS-MAC=00:01:5c:6b:de:50;CM-QOS=1.1;CM-VER=3.0;

 Mon Apr 15 08:54:53 2019     Critical (3)        Resetting the cable modem due to docsDevResetNow

 Time Not Established              Critical (3)        No Ranging Response received - T3 time-out;CM-MAC=00:40:36:50:78:1e;CMTS-MAC=00:01:5c:6b:de:50;CM-QOS=1.0;CM-VER=3.0;

 Mon Apr 15 09:06:32 2019     Critical (3)        Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=00:40:36:50:78:1e;CMTS-MAC=00:01:5c:6b:de:50;CM-QOS=1.1;CM-VER=3.0;

 Time Not Established              Critical (3)        No Ranging Response received - T3 time-out;CM-MAC=00:40:36:50:78:1e;CMTS-MAC=00:01:5c:6b:de:50;CM-QOS=1.0;CM-VER=3.0;

 Mon Apr 15 09:09:08 2019     Critical (3)        Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=00:40:36:50:78:1e;CMTS-MAC=00:01:5c:6b:de:50;CM-QOS=1.1;CM-VER=3.0;

 Mon Apr 15 09:17:43 2019     Critical (3)        Resetting the cable modem due to docsDevResetNow

 Mon Apr 15 10:23:20 2019     Critical (3)        Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=00:40:36:50:78:1e;CMTS-MAC=00:01:5c:6b:de:50;CM-QOS=1.1;CM-VER=3.0;

 Time Not Established              Critical (3)        No Ranging Response received - T3 time-out;CM-MAC=00:40:36:50:78:1e;CMTS-MAC=00:01:5c:6b:de:50;CM-QOS=1.0;CM-VER=3.0;

 Mon Apr 15 10:24:25 2019     Critical (3)        Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=00:40:36:50:78:1e;CMTS-MAC=00:01:5c:6b:de:50;CM-QOS=1.1;CM-VER=3.0;

 Time Not Established              Critical (3)        No Ranging Response received - T3 time-out;CM-MAC=00:40:36:50:78:1e;CMTS-MAC=00:01:5c:6b:de:50;CM-QOS=1.0;CM-VER=3.0;

 Mon Apr 15 11:04:28 2019     Critical (3)        Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=00:40:36:50:78:1e;CMTS-MAC=00:01:5c:6b:de:50;CM-QOS=1.1;CM-VER=3.0;

 Time Not Established              Critical (3)        No Ranging Response received - T3 time-out;CM-MAC=00:40:36:50:78:1e;CMTS-MAC=00:01:5c:6b:de:50;CM-QOS=1.0;CM-VER=3.0;

 Wed Apr 17 13:42:42 2019     Critical (3)        Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=00:40:36:50:78:1e;CMTS-MAC=00:01:5c:6b:de:50;CM-QOS=1.1;CM-VER=3.0;

 Time Not Established              Critical (3)        No Ranging Response received - T3 time-out;CM-MAC=00:40:36:50:78:1e;CMTS-MAC=00:01:5c:6b:de:50;CM-QOS=1.0;CM-VER=3.0;

 Time Not Established              Notice (6)        Honoring MDD; IP provisioning mode = IPv6

 Fri Apr 19 16:48:32 2019        Critical (3)        Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=00:40:36:50:78:1e;CMTS-MAC=00:01:5c:6b:de:50;CM-QOS=1.1;CM-VER=3.0;

 Fri Apr 19 16:52:52 2019        Critical (3)        Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=00:40:36:50:78:1e;CMTS-MAC=00:01:5c:6b:de:50;CM-QOS=1.1;CM-VER=3.0;

 Fri Apr 19 16:53:06 2019        Notice (6)        Honoring MDD; IP provisioning mode = IPv6

 Fri Apr 19 17:21:35 2019        Critical (3)        SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=00:40:36:50:78:1e;CMTS-MAC=00:01:5c:6b:de:50;CM-QOS=1.1;CM-VER=3.0;

 Fri Apr 19 17:21:36 2019        Critical (3)        SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=00:40:36:50:78:1e;CMTS-MAC=00:01:5c:6b:de:50;CM-QOS=1.1;CM-VER=3.0;

 Fri Apr 19 17:21:39 2019        Warning (5)     MDD message timeout;CM-MAC=00:40:36:50:78:1e;CMTS-MAC=00:01:5c:6b:de:50;CM-QOS=1.1;CM-VER=3.0;

 Fri Apr 19 17:21:56 2019        Critical (3)        Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=00:40:36:50:78:1e;CMTS-MAC=00:01:5c:6b:de:50;CM-QOS=1.1;CM-VER=3.0;

                       

Expert

Re: intermittent outages, slow upload speed, normal download speed

The error log entries indicate that something is going on. Perhaps there is 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.

 

You can call in and ask what these figures are. The Upstream Receive Power Level should fall within the range of -2dB to +2dB with 0dB being in the middle and perfect.

The Upstream SNR should be least 31dB, and the higher it is the better.

The ICFR should be no higher than 2 dB.

They will be able to see whether or not everything is in the green zone and also see a history plot for the modem. Good luck !




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New Poster

Re: intermittent outages, slow upload speed, normal download speed

Thank you very much.  I'll try Comcast again.  They like to recommend resetting the modem to factory settings, which means a nuisance of re-entering passwords, etc.  But am I right that the problem is almost certainly elsewhere, as with the possibility of noise on the line you mention?

       And if that's the case, if they send out a technician, should I try to get him or her to check all the line connections, all the way out to the telephone pole?  Do you recommend any other specific checks to be made?

Expert

Re: intermittent outages, slow upload speed, normal download speed

Any tech that is *worth their salt* will know what to do. Show them this thread. 

 

Bear in mind that if the premises facing techs can not find or fix a problem at your home, it is they who are responsible for escalating it to their line / network / maintenance dept. techs. The problem may indeed lie beyond your home in the local neighborhood infrastructure somewhere but it is their S.O.P. to start at the home.




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New Poster

Re: intermittent outages, slow upload speed, normal download speed

And thanks again.

Expert

Re: intermittent outages, slow upload speed, normal download speed

Quite welcome ! Please post back with how things turn out.



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