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Frequent T3 errors causing dropped connections

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Regular Visitor

Frequent T3 errors causing dropped connections

I work from home due to the pandemic. Several times a day during conference calls or using remote desktop, my connection drops. The problem is so frequent it is measurably impacting my ability to work with others. Lately the problem has been getting worse, so I've increased the number of times I call technical support. Unfortunately, each time the same scripted help is followed, and the problem hasn't been resovled. I desparately hope someone here can help by looking at technical details in this post.

 

Each connection drop corresponds with an entry in my modem's error log (see bottom of this post). The modem is a Netgear CM1000v2. I've read many techincal help documents, including the recommend (and helpful) "Internet Troubleshooting Tips" post that is recommended on this message board to others.

 

So far, it looks like my connection statistics are within recommended ranges (downstream and upstream levels, SNR, etc...). Downstream is a little high, and can be dropped down using a forward path attenuator, but tends to fluctuate. There are a large amount of Uncorrectable Codewords. There are also many Dynamic Range Window violation errors in the logs.

 

What I've done to troubleshoot the issue is (various combinations of the below):

- Remove all splitters

- Remove all house COAX runs

- Insert a 3.5dB Antronix CMC2002H-A splitter with terminated end caps for unused ports

- Insert a 7dB Comscope 5-1000mHz splitter with terminated end caps for unused ports

- Insert a 6dB forward path attenuator to decrease only downstream power (PPC FPA6-54)

- Tried another modem: ARRIS SB6183 (similar T3 errors reported)

 

What Comcast has done:

- Insert a 3.5dB Comscope 5-1000mHz splitter with terminated end caps for unused ports

 

I've tried all I can think of to fix the problem on my end. I suspect the issue is outside of my home at the tap or further away. The one time I was able to get a technition out to my house, he wasn't willing to check the tap on the pole and instead installed a 3.5dB splitter to lower the signal strength coming into my home.

 

Thank you in advance for reviewing this information!

 

The below data is with a 3.5dB Antronix splitter installed.

TimePriorityDescription
2020-09-02, 18:57:16Critical (3)Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=bc:a5:11:89:db:f4;CMTS-MAC=58:97:bd:98:4a:ad;CM-QOS=1.1;CM-VER=3.1;
2020-09-02, 18:52:16Warning (5)Dynamic Range Window violation
2020-09-02, 18:52:16Warning (5)RNG-RSP CCAP Commanded Power Exceeds Value Corresponding to the Top of the DRW;CM-MAC=bc:a5:11:89:db:f4;CMTS-MAC=58:97:bd:98:4a:ad;CM-QOS=1.1;CM-VER=3.1;
2020-09-02, 18:51:15Warning (5)Dynamic Range Window violation
2020-09-02, 18:51:15Warning (5)RNG-RSP CCAP Commanded Power in Excess of 6 dB Below the Value Corresponding to the Top of the DRW;CM-MAC=bc:a5:11:89:db:f4;CMTS-MAC=58:97:bd:98:4a:ad;CM-QOS=1.1;CM-VER=3.1;
2020-09-02, 18:51:15Warning (5)Dynamic Range Window violation
2020-09-02, 18:51:15Warning (5)RNG-RSP CCAP Commanded Power in Excess of 6 dB Below the Value Corresponding to the Top of the DRW;CM-MAC=bc:a5:11:89:db:f4;CMTS-MAC=58:97:bd:98:4a:ad;CM-QOS=1.1;CM-VER=3.1;
2020-09-02, 18:51:15Warning (5)Dynamic Range Window violation
2020-09-02, 18:51:15Warning (5)RNG-RSP CCAP Commanded Power in Excess of 6 dB Below the Value Corresponding to the Top of the DRW;CM-MAC=bc:a5:11:89:db:f4;CMTS-MAC=58:97:bd:98:4a:ad;CM-QOS=1.1;CM-VER=3.1;
2020-09-02, 18:51:15Warning (5)Dynamic Range Window violation
2020-09-02, 18:51:15Warning (5)RNG-RSP CCAP Commanded Power in Excess of 6 dB Below the Value Corresponding to the Top of the DRW;CM-MAC=bc:a5:11:89:db:f4;CMTS-MAC=58:97:bd:98:4a:ad;CM-QOS=1.1;CM-VER=3.1;
2020-09-02, 15:09:21Critical (3)Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=bc:a5:11:89:db:f4;CMTS-MAC=58:97:bd:98:4a:ad;CM-QOS=1.1;CM-VER=3.1;
2020-09-02, 15:05:14Warning (5)Dynamic Range Window violation
2020-09-02, 15:05:14Warning (5)RNG-RSP CCAP Commanded Power in Excess of 6 dB Below the Value Corresponding to the Top of the DRW;CM-MAC=bc:a5:11:89:db:f4;CMTS-MAC=58:97:bd:98:4a:ad;CM-QOS=1.1;CM-VER=3.1;
2020-09-02, 15:05:14Warning (5)Dynamic Range Window violation
2020-09-02, 15:05:14Warning (5)RNG-RSP CCAP Commanded Power in Excess of 6 dB Below the Value Corresponding to the Top of the DRW;CM-MAC=bc:a5:11:89:db:f4;CMTS-MAC=58:97:bd:98:4a:ad;CM-QOS=1.1;CM-VER=3.1;
2020-09-02, 15:05:14Warning (5)Dynamic Range Window violation
2020-09-02, 15:05:14Warning (5)RNG-RSP CCAP Commanded Power in Excess of 6 dB Below the Value Corresponding to the Top of the DRW;CM-MAC=bc:a5:11:89:db:f4;CMTS-MAC=58:97:bd:98:4a:ad;CM-QOS=1.1;CM-VER=3.1;
2020-09-02, 15:05:14Warning (5)Dynamic Range Window violation
2020-09-02, 15:05:14Warning (5)RNG-RSP CCAP Commanded Power in Excess of 6 dB Below the Value Corresponding to the Top of the DRW;CM-MAC=bc:a5:11:89:db:f4;CMTS-MAC=58:97:bd:98:4a:ad;CM-QOS=1.1;CM-VER=3.1;
2020-09-02, 13:28:04Warning (5)Dynamic Range Window violation
2020-09-02, 13:28:04Warning (5)RNG-RSP CCAP Commanded Power Exceeds Value Corresponding to the Top of the DRW;CM-MAC=bc:a5:11:89:db:f4;CMTS-MAC=58:97:bd:98:4a:ad;CM-QOS=1.1;CM-VER=3.1;
2020-09-02, 13:26:43Warning (5)Dynamic Range Window violation
2020-09-02, 13:26:43Warning (5)RNG-RSP CCAP Commanded Power in Excess of 6 dB Below the Value Corresponding to the Top of the DRW;CM-MAC=bc:a5:11:89:db:f4;CMTS-MAC=58:97:bd:98:4a:ad;CM-QOS=1.1;CM-VER=3.1;
2020-09-02, 13:26:43Warning (5)Dynamic Range Window violation
2020-09-02, 13:26:43Warning (5)RNG-RSP CCAP Commanded Power in Excess of 6 dB Below the Value Corresponding to the Top of the DRW;CM-MAC=bc:a5:11:89:db:f4;CMTS-MAC=58:97:bd:98:4a:ad;CM-QOS=1.1;CM-VER=3.1;
2020-09-02, 13:26:43Warning (5)Dynamic Range Window violation
2020-09-02, 13:26:43Warning (5)RNG-RSP CCAP Commanded Power in Excess of 6 dB Below the Value Corresponding to the Top of the DRW;CM-MAC=bc:a5:11:89:db:f4;CMTS-MAC=58:97:bd:98:4a:ad;CM-QOS=1.1;CM-VER=3.1;
2020-09-02, 13:26:43Warning (5)Dynamic Range Window violation
2020-09-02, 13:26:43Warning (5)RNG-RSP CCAP Commanded Power in Excess of 6 dB Below the Value Corresponding to the Top of the DRW;CM-MAC=bc:a5:11:89:db:f4;CMTS-MAC=58:97:bd:98:4a:ad;CM-QOS=1.1;CM-VER=3.1;
2020-09-02, 11:48:31Warning (5)Dynamic Range Window violation
2020-09-02, 11:48:31Warning (5)RNG-RSP CCAP Commanded Power in Excess of 6 dB Below the Value Corresponding to the Top of the DRW;CM-MAC=bc:a5:11:89:db:f4;CMTS-MAC=58:97:bd:98:4a:ad;CM-QOS=1.1;CM-VER=3.1;
2020-09-02, 11:48:31Warning (5)Dynamic Range Window violation
2020-09-02, 11:48:31Warning (5)RNG-RSP CCAP Commanded Power in Excess of 6 dB Below the Value Corresponding to the Top of the DRW;CM-MAC=bc:a5:11:89:db:f4;CMTS-MAC=58:97:bd:98:4a:ad;CM-QOS=1.1;CM-VER=3.1;
2020-09-01, 16:41:52Warning (5)Dynamic Range Window violation
2020-09-01, 16:41:52Warning (5)RNG-RSP CCAP Commanded Power in Excess of 6 dB Below the Value Corresponding to the Top of the DRW;CM-MAC=bc:a5:11:89:db:f4;CMTS-MAC=58:97:bd:98:4a:ad;CM-QOS=1.1;CM-VER=3.1;
2020-09-01, 16:41:52Warning (5)Dynamic Range Window violation
2020-09-01, 16:41:52Warning (5)RNG-RSP CCAP Commanded Power in Excess of 6 dB Below the Value Corresponding to the Top of the DRW;CM-MAC=bc:a5:11:89:db:f4;CMTS-MAC=58:97:bd:98:4a:ad;CM-QOS=1.1;CM-VER=3.1;
2020-09-01, 16:41:32Critical (3)Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=bc:a5:11:89:db:f4;CMTS-MAC=58:97:bd:98:4a:ad;CM-QOS=1.1;CM-VER=3.1;
2020-09-01, 16:11:53Warning (5)Dynamic Range Window violation

 

 
ChannelLock StatusModulationChannel IDFrequencyPowerSNR / MERUnerrored CodewordsCorrectable CodewordsUncorrectable Codewords
1LockedQAM25625597000000 Hz3.5 dBmV40.5 dB37734963411874870
2LockedQAM2561447000000 Hz5.0 dBmV41.4 dB3772458918581927
3LockedQAM2562453000000 Hz5.1 dBmV41.5 dB37724657516031363
4LockedQAM2563459000000 Hz5.1 dBmV41.4 dB37724676085251137
5LockedQAM2564465000000 Hz5.1 dBmV41.6 dB37724740045341120
6LockedQAM2565471000000 Hz5.2 dBmV41.5 dB37724736605181155
7LockedQAM2566477000000 Hz5.1 dBmV41.3 dB37724806105491055
8LockedQAM2567483000000 Hz5.0 dBmV41.5 dB37724818645361036
9LockedQAM2568489000000 Hz4.9 dBmV41.4 dB37724999035881057
10LockedQAM2569495000000 Hz4.8 dBmV41.0 dB3772506365570941
11LockedQAM25610507000000 Hz4.8 dBmV41.4 dB3772504220667947
12LockedQAM25611513000000 Hz4.8 dBmV41.3 dB37725106286181022
13LockedQAM25612519000000 Hz4.7 dBmV41.3 dB37725192177001076
14LockedQAM25613525000000 Hz4.5 dBmV41.1 dB3772521650831997
15LockedQAM25614531000000 Hz4.4 dBmV41.0 dB3733496952787664
16LockedQAM25615537000000 Hz4.4 dBmV41.1 dB37725279367941084
17LockedQAM25616543000000 Hz4.2 dBmV41.0 dB3772566902828934
18LockedQAM25617549000000 Hz4.1 dBmV41.1 dB3772566644996867
19LockedQAM25618555000000 Hz3.9 dBmV40.8 dB377256939910771024
20LockedQAM25619561000000 Hz3.8 dBmV40.8 dB37725774741372894
21LockedQAM25620567000000 Hz3.8 dBmV40.6 dB37725783411308901
22LockedQAM25621573000000 Hz3.7 dBmV40.9 dB37725802601377927
23LockedQAM25622579000000 Hz3.6 dBmV40.6 dB377258966414661002
24LockedQAM25623585000000 Hz3.7 dBmV40.7 dB377259251114151110
25LockedQAM25624591000000 Hz3.6 dBmV40.5 dB37725965631677840
26LockedQAM25626603000000 Hz3.5 dBmV40.5 dB37725966752135783
27LockedQAM25627609000000 Hz3.4 dBmV40.3 dB37726027822255856
28LockedQAM25628615000000 Hz3.4 dBmV40.2 dB37726026672354796
29LockedQAM25629621000000 Hz3.4 dBmV40.1 dB37726080462397819
30LockedQAM25630627000000 Hz3.3 dBmV40.0 dB377261265829031014
31LockedQAM25631633000000 Hz3.2 dBmV39.9 dB37726107893270849
32LockedQAM25632639000000 Hz3.2 dBmV40.0 dB37726117073399828

 
ChannelLock StatusModulationChannel IDFrequencyPower
1LockedATDMA135600000 Hz42.5 dBmV
2LockedATDMA229200000 Hz41.5 dBmV
3LockedATDMA322800000 Hz41.0 dBmV
4LockedATDMA416400000 Hz41.5 dBmV
5LockedATDMA539600000 Hz43.0 dBmV
6Not LockedUnknown00 Hz0.0 dBmV
7Not LockedUnknown00 Hz0.0 dBmV
8Not LockedUnknown00 Hz0.0 dBmV

 
ChannelLock StatusModulation / Profile IDChannel IDFrequencyPowerSNR / MERActive Subcarrier Number RangeUnerrored CodewordsCorrectable CodewordsUncorrectable Codewords
1Locked0, 1159768000000 Hz3.7 dBmV38.8 dB1126 ~ 296970214634467132380
2Not Locked000 Hz4.7 dBmV0.0 dB0 ~ 4095000
Highlighted
Expert

Re: Frequent T3 errors causing dropped connections

The signal stats are o/k but 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.

 

I'm going to escalate your issue to the Comcast corporate employees that are available to these boards. They will be able to poll the CMTS to see whether or not everything is in the green zone, see your node / cable plant and modem health, and also see a history plot for the modem. You should get a reply here in your topic. Good luck !



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

Re: Frequent T3 errors causing dropped connections

Thank you very much!

Highlighted
Expert

Re: Frequent T3 errors causing dropped connections

Quite welcome !



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!