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Internet keeps dropping randomly through out the day - T3 time-out in Logs

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Internet keeps dropping randomly through out the day - T3 time-out in Logs

Hello guys,

My internet keeps on dropping randomly throughout the day then it connects back up after 5 to 10 min later.  This had happened to me a few years ago and they had to put in a new cable in the back from the junction box to my house and it worked fine up to last week. I am having the same issue that I did, my speed has gone down and also the connection is also been flaky. I have troubleshot this with the best of my ability and it looks like there is some sort of signal issue from the junction box to my house or something. As I am seeing T3 time-out in my modem logs when the internet disconnects. We work from home and this is really affecting our productivity. Like the following:

Mon Apr 20 07:38:25 2020 Warning (5) MDD message timeout;CM-MAC=xxxxxx;CMTS-MAC=xxxxxx;CM-QOS=1.1;CM-VER=3.0;
Mon Apr 20 07:38:25 2020 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=xxxxxx;CMTS-MAC=xxxxxx;CM-QOS=1.1;CM-VER=3.0;
Mon Apr 20 07:39:12 2020 Warning (5) MDD message timeout;CM-MAC=xxxxxxCMTS-MAC=xxxxxx;CM-QOS=1.1;CM-VER=3.0;
Mon Apr 20 07:39:12 2020 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=xxxxxx;CMTS-MAC=xxxxxx;CM-QOS=1.1;CM-VER=3.0;
Mon Apr 20 07:40:23 2020 Warning (5) MDD message timeout;CM-MAC=xxxxxx;CMTS-MAC=xxxxxx;CM-QOS=1.1;CM-VER=3.0;
Mon Apr 20 07:40:23 2020 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=xxxxxx;CMTS-MAC=xxxxxx;CM-QOS=1.1;CM-VER=3.0;
Mon Apr 20 07:55:57 2020 Warning (5) MDD message timeout;CM-MAC=xxxxxx;CMTS-MAC=xxxxxx;CM-QOS=1.1;CM-VER=3.0;

 

Also, my signal snapshot is here:

 
Downstream Bonded Channels
Channel Lock Status Modulation Channel ID Frequency Power SNR Corrected Uncorrectables
1 Locked QAM256 17 621000000 Hz 5.0 dBmV 39.2 dB 71010864 38503806
2 Locked QAM256 18 627000000 Hz 5.1 dBmV 35.3 dB 38274307 182122361
3 Locked QAM256 19 633000000 Hz 5.2 dBmV 39.2 dB 41945168 200454010
4 Locked QAM256 20 639000000 Hz 5.1 dBmV 29.8 dB 8847032 6099722
5 Locked QAM256 21 645000000 Hz 5.0 dBmV 0.0 dB 786846 4276852
6 Locked QAM256 22 651000000 Hz 4.9 dBmV 37.7 dB 33423600 17075206
7 Locked QAM256 23 657000000 Hz 4.7 dBmV 41.4 dB 0 0
8 Locked QAM256 24 663000000 Hz 4.4 dBmV 41.3 dB 0 0
9 Locked QAM256 25 669000000 Hz 4.6 dBmV 41.6 dB 17 55
10 Locked QAM256 26 675000000 Hz 4.4 dBmV 40.8 dB 21 69
11 Locked QAM256 27 681000000 Hz 4.3 dBmV 41.6 dB 24 93
12 Locked QAM256 28 687000000 Hz 4.2 dBmV 41.6 dB 22 71
13 Locked QAM256 29 693000000 Hz 3.9 dBmV 41.4 dB 17 68
14 Locked QAM256 30 699000000 Hz 3.9 dBmV 41.5 dB 6 43
15 Locked QAM256 31 705000000 Hz 3.9 dBmV 41.6 dB 17 66
16 Locked QAM256 32 711000000 Hz 4.1 dBmV 41.8 dB 15 79

 

 
Upstream Bonded Channels
Channel Lock Status US Channel Type Channel ID Symbol Rate Frequency Power
1 Locked ATDMA 4 5120 Ksym/sec 16600000 Hz 41.0 dBmV
2 Locked ATDMA 1 5120 Ksym/sec 35800000 Hz 39.5 dBmV
3 Locked ATDMA 2 5120 Ksym/sec 29400000 Hz 40.5 dBmV
4 Locked ATDMA 3 5120 Ksym/sec 23000000 Hz 40.3 dBmV
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Expert

Re: Internet keeps dropping randomly through out the day - T3 time-out in Logs

The SNR is too low / out of spec on some of the downstream channels. Seems that there is some noise ingressing into the line(s) somewhere at those frequencies. That can cause random disconnects, spontaneous re-booting of the modem, speed, packet loss, 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.



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New Poster

Re: Internet keeps dropping randomly through out the day - T3 time-out in Logs

Thank you for the reply, I have no splitters in my house. I went through this troubleshooting and learned my lesson a couple of years ago, so now I have a straight cable that comes into the modem from outside.  What is the range of ideal SNRs?

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Expert

Re: Internet keeps dropping randomly through out the day - T3 time-out in Logs

Specification      Min             Max
Downstream Power Level    
Cable Modems -10dBmV +10dBmV
Gateways and EMTAs -7dBmV +7dBmV
Downstream Signal to Noise Ratio 35dB -
Upstream Power Level +35dBmV +50dBmV
Upstream Signal to Noise Ratio 31dB -
Upstream Receive Power -2dBmV +2dBmV

 

Then you'll need a tech out to investigate. 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 lie beyond your home in the local neighborhood infrastructure somewhere but it is their S.O.P. to start at the home.

Good luck with it !



I am not a Comcast Employee.
I am a Customer Expert volunteering my time to help other customers here in the Forums.
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!