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.

Time	Priority	Description
2020-09-02, 18:57:16	Critical (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, 18:52:16	Warning (5)	Dynamic Range Window violation
2020-09-02, 18:52:16	Warning (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, 18:51:15	Warning (5)	Dynamic Range Window violation
2020-09-02, 18:51:15	Warning (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, 18:51:15	Warning (5)	Dynamic Range Window violation
2020-09-02, 18:51:15	Warning (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, 18:51:15	Warning (5)	Dynamic Range Window violation
2020-09-02, 18:51:15	Warning (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, 18:51:15	Warning (5)	Dynamic Range Window violation
2020-09-02, 18:51:15	Warning (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, 15:09:21	Critical (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, 15:05:14	Warning (5)	Dynamic Range Window violation
2020-09-02, 15:05:14	Warning (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, 15:05:14	Warning (5)	Dynamic Range Window violation
2020-09-02, 15:05:14	Warning (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, 15:05:14	Warning (5)	Dynamic Range Window violation
2020-09-02, 15:05:14	Warning (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, 15:05:14	Warning (5)	Dynamic Range Window violation
2020-09-02, 15:05:14	Warning (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, 13:28:04	Warning (5)	Dynamic Range Window violation
2020-09-02, 13:28:04	Warning (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, 13:26:43	Warning (5)	Dynamic Range Window violation
2020-09-02, 13:26:43	Warning (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, 13:26:43	Warning (5)	Dynamic Range Window violation
2020-09-02, 13:26:43	Warning (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, 13:26:43	Warning (5)	Dynamic Range Window violation
2020-09-02, 13:26:43	Warning (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, 13:26:43	Warning (5)	Dynamic Range Window violation
2020-09-02, 13:26:43	Warning (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, 11:48:31	Warning (5)	Dynamic Range Window violation
2020-09-02, 11:48:31	Warning (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, 11:48:31	Warning (5)	Dynamic Range Window violation
2020-09-02, 11:48:31	Warning (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, 16:41:52	Warning (5)	Dynamic Range Window violation
2020-09-01, 16:41:52	Warning (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, 16:41:52	Warning (5)	Dynamic Range Window violation
2020-09-01, 16:41:52	Warning (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, 16:41:32	Critical (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, 16:11:53	Warning (5)	Dynamic Range Window violation

Channel	Lock Status	Modulation	Channel ID	Frequency	Power	SNR / MER	Unerrored Codewords	Correctable Codewords	Uncorrectable Codewords
1	Locked	QAM256	25	597000000 Hz	3.5 dBmV	40.5 dB	3773496341	1874	870
2	Locked	QAM256	1	447000000 Hz	5.0 dBmV	41.4 dB	3772458918	581	927
3	Locked	QAM256	2	453000000 Hz	5.1 dBmV	41.5 dB	3772465751	603	1363
4	Locked	QAM256	3	459000000 Hz	5.1 dBmV	41.4 dB	3772467608	525	1137
5	Locked	QAM256	4	465000000 Hz	5.1 dBmV	41.6 dB	3772474004	534	1120
6	Locked	QAM256	5	471000000 Hz	5.2 dBmV	41.5 dB	3772473660	518	1155
7	Locked	QAM256	6	477000000 Hz	5.1 dBmV	41.3 dB	3772480610	549	1055
8	Locked	QAM256	7	483000000 Hz	5.0 dBmV	41.5 dB	3772481864	536	1036
9	Locked	QAM256	8	489000000 Hz	4.9 dBmV	41.4 dB	3772499903	588	1057
10	Locked	QAM256	9	495000000 Hz	4.8 dBmV	41.0 dB	3772506365	570	941
11	Locked	QAM256	10	507000000 Hz	4.8 dBmV	41.4 dB	3772504220	667	947
12	Locked	QAM256	11	513000000 Hz	4.8 dBmV	41.3 dB	3772510628	618	1022
13	Locked	QAM256	12	519000000 Hz	4.7 dBmV	41.3 dB	3772519217	700	1076
14	Locked	QAM256	13	525000000 Hz	4.5 dBmV	41.1 dB	3772521650	831	997
15	Locked	QAM256	14	531000000 Hz	4.4 dBmV	41.0 dB	3733496952	787	664
16	Locked	QAM256	15	537000000 Hz	4.4 dBmV	41.1 dB	3772527936	794	1084
17	Locked	QAM256	16	543000000 Hz	4.2 dBmV	41.0 dB	3772566902	828	934
18	Locked	QAM256	17	549000000 Hz	4.1 dBmV	41.1 dB	3772566644	996	867
19	Locked	QAM256	18	555000000 Hz	3.9 dBmV	40.8 dB	3772569399	1077	1024
20	Locked	QAM256	19	561000000 Hz	3.8 dBmV	40.8 dB	3772577474	1372	894
21	Locked	QAM256	20	567000000 Hz	3.8 dBmV	40.6 dB	3772578341	1308	901
22	Locked	QAM256	21	573000000 Hz	3.7 dBmV	40.9 dB	3772580260	1377	927
23	Locked	QAM256	22	579000000 Hz	3.6 dBmV	40.6 dB	3772589664	1466	1002
24	Locked	QAM256	23	585000000 Hz	3.7 dBmV	40.7 dB	3772592511	1415	1110
25	Locked	QAM256	24	591000000 Hz	3.6 dBmV	40.5 dB	3772596563	1677	840
26	Locked	QAM256	26	603000000 Hz	3.5 dBmV	40.5 dB	3772596675	2135	783
27	Locked	QAM256	27	609000000 Hz	3.4 dBmV	40.3 dB	3772602782	2255	856
28	Locked	QAM256	28	615000000 Hz	3.4 dBmV	40.2 dB	3772602667	2354	796
29	Locked	QAM256	29	621000000 Hz	3.4 dBmV	40.1 dB	3772608046	2397	819
30	Locked	QAM256	30	627000000 Hz	3.3 dBmV	40.0 dB	3772612658	2903	1014
31	Locked	QAM256	31	633000000 Hz	3.2 dBmV	39.9 dB	3772610789	3270	849
32	Locked	QAM256	32	639000000 Hz	3.2 dBmV	40.0 dB	3772611707	3399	828

Channel	Lock Status	Modulation	Channel ID	Frequency	Power
1	Locked	ATDMA	1	35600000 Hz	42.5 dBmV
2	Locked	ATDMA	2	29200000 Hz	41.5 dBmV
3	Locked	ATDMA	3	22800000 Hz	41.0 dBmV
4	Locked	ATDMA	4	16400000 Hz	41.5 dBmV
5	Locked	ATDMA	5	39600000 Hz	43.0 dBmV
6	Not Locked	Unknown	0	0 Hz	0.0 dBmV
7	Not Locked	Unknown	0	0 Hz	0.0 dBmV
8	Not Locked	Unknown	0	0 Hz	0.0 dBmV

Channel	Lock Status	Modulation / Profile ID	Channel ID	Frequency	Power	SNR / MER	Active Subcarrier Number Range	Unerrored Codewords	Correctable Codewords	Uncorrectable Codewords
1	Locked	0, 1	159	768000000 Hz	3.7 dBmV	38.8 dB	1126 ~ 2969	7021463446	713238	0
2	Not Locked	0	0	0 Hz	4.7 dBmV	0.0 dB	0 ~ 4095	0	0	0

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Responses

EG

Expert

•

111.4K Messages

5 years ago

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 !

rquellet

Regular Visitor

•

2 Messages

5 years ago

Thank you very much!

EG

Expert

•

111.4K Messages

5 years ago

Quite welcome !

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rquellet

Frequent T3 errors causing dropped connections

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