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Connection drops several times per day - Started Unicast Maintenance Ranging - No Response received

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Connection drops several times per day - Started Unicast Maintenance Ranging - No Response received

Have had an issue now for a few weeks where my home internet connection is dropping for about 7-10 minutes at a time, up to 8-10 times a day.  

 

Just started happening about a month ago, and I did see several Comcast vans in the neighborhood around that time, so I'm thinking something got mucked up.

 

Anyway, I have a CM600 modem and the event log is showing the following at the times of the drops:

2020-06-30, 10:34:46 Critical (3) Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=78:d2:94:f9:dc:40;CMTS-MAC=00:01:5c:b1:46:67;CM-QOS=1.1;CM-VER=3.0;
2020-06-30, 10:30:28 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=78:d2:94:f9:dc:40;CMTS-MAC=00:01:5c:b1:46:67;CM-QOS=1.1;CM-VER=3.0;
2020-06-30, 10:30:23 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=78:d2:94:f9:dc:40;CMTS-MAC=00:01:5c:b1:46:67;CM-QOS=1.1;CM-VER=3.0;
2020-06-30, 10:30:23 Critical (3) Unicast Maintenance Ranging attempted - No response - Retries exhausted;CM-MAC=78:d2:94:f9:dc:40;CMTS-MAC=00:01:5c:b1:46:67;CM-QOS=1.1;CM-VER=3.0;
2020-06-30, 10:30:23 Critical (3) 16 consecutive T3 timeouts while trying to range on upstream channel 2;CM-MAC=78:d2:94:f9:dc:40;CMTS-MAC=00:01:5c:b1:46:67;CM-QOS=1.1;CM-VER=3.0;
2020-06-30, 10:30:04 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=78:d2:94:f9:dc:40;CMTS-MAC=00:01:5c:b1:46:67;CM-QOS=1.1;CM-VER=3.0;
2020-06-30, 10:30:04 Critical (3) Unicast Maintenance Ranging attempted - No response - Retries exhausted;CM-MAC=78:d2:94:f9:dc:40;CMTS-MAC=00:01:5c:b1:46:67;CM-QOS=1.1;CM-VER=3.0;
2020-06-30, 10:30:04 Critical (3) 16 consecutive T3 timeouts while trying to range on upstream channel 3;CM-MAC=78:d2:94:f9:dc:40;CMTS-MAC=00:01:5c:b1:46:67;CM-QOS=1.1;CM-VER=3.0;

 

I've checked all cables, reset modem multiple times, checked outage maps during times I've lost connection, and found no answer to this yet.  Comcast chat agent said everything looked good from what they could see and just reset the modem again, which works for a while, but then we start getting drops anywhere from 10 mins to 5 hours later.

 

Is this a line problem or a modem problem?

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Expert

Re: Connection drops several times per day - Started Unicast Maintenance Ranging - No Response rece

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




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Re: Connection drops several times per day - Started Unicast Maintenance Ranging - No Response rece

Here you go -- 

 

<tabindex=-1>Downstream Bonded Channels</tabindex=-1>
Channel Lock Status Modulation Channel ID Frequency Power SNR Correctables Uncorrectables
1 Locked QAM256 17 435000000 Hz -2.2 dBmV 39.9 dB 3322 3055
2 Locked QAM256 1 339000000 Hz -0.7 dBmV 40.8 dB 3771 2268
3 Locked QAM256 2 345000000 Hz -0.8 dBmV 40.6 dB 2875 1063
4 Locked QAM256 3 351000000 Hz -0.6 dBmV 40.7 dB 3325 2437
5 Locked QAM256 4 357000000 Hz -0.6 dBmV 40.7 dB 3197 1959
6 Locked QAM256 5 363000000 Hz -0.8 dBmV 40.6 dB 2970 1522
7 Locked QAM256 6 369000000 Hz -1.1 dBmV 40.3 dB 3624 1154
8 Locked QAM256 7 375000000 Hz -1.4 dBmV 40.3 dB 2810 1940
9 Locked QAM256 8 381000000 Hz -1.4 dBmV 40.2 dB 3607 1143
10 Locked QAM256 9 387000000 Hz -1.8 dBmV 40.2 dB 2283 995
11 Locked QAM256 10 393000000 Hz -1.3 dBmV 40.2 dB 3584 1124
12 Locked QAM256 11 399000000 Hz -1.7 dBmV 40.1 dB 2111 877
13 Locked QAM256 12 405000000 Hz -1.5 dBmV 40.1 dB 2826 1078
14 Locked QAM256 13 411000000 Hz -2.0 dBmV 40.0 dB 1975 750
15 Locked QAM256 14 417000000 Hz -1.7 dBmV 40.0 dB 2145 963
16 Locked QAM256 15 423000000 Hz -1.9 dBmV 40.0 dB 1695 853
17 Locked QAM256 16 429000000 Hz -2.1 dBmV 40.4 dB 0 0
18 Locked QAM256 18 441000000 Hz -2.8 dBmV 40.3 dB 0 0
19 Locked QAM256 19 453000000 Hz -3.0 dBmV 39.9 dB 0 0
20 Locked QAM256 20 459000000 Hz -2.7 dBmV 39.9 dB 0 0
21 Locked QAM256 21 465000000 Hz -2.9 dBmV 40.0 dB 0 0
22 Locked QAM256 22 471000000 Hz -2.6 dBmV 40.1 dB 0 0
23 Locked QAM256 23 477000000 Hz -2.7 dBmV 40.0 dB 0 0
24 Locked QAM256 24 483000000 Hz -2.5 dBmV 40.3 dB 0 0

 

<tabindex=-1>Upstream Bonded Channels</tabindex=-1>
Channel Lock Status US Channel Type Channel ID Symbol Rate Frequency Power
1 Locked ATDMA 4 5120 Ksym/sec 16600000 Hz 50.8 dBmV
2 Locked ATDMA 1 5120 Ksym/sec 35800000 Hz 51.3 dBmV
3 Locked ATDMA 2 5120 Ksym/sec 29400000 Hz 51.8 dBmV
4 Locked ATDMA 3 5120 Ksym/sec 23000000 Hz 51.8 dBmV
5 Not Locked Unknown 0 0 Ksym/sec 0 Hz 0.0 dBmV
6 Not Locked Unknown 0 0 Ksym/sec 0 Hz 0.0 dBmV
7 Not Locked Unknown 0 0 Ksym/sec 0 Hz 0.0 dBmV
8 Not Locked Unknown 0 0 Ksym/sec 0 Hz 0.0 dBmV
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Expert

Re: Connection drops several times per day - Started Unicast Maintenance Ranging - No Response rece

The upstream power is too high and it may be intermittently fluctuating even higher to out of spec levels. That can cause random disconnects, spontaneous re-booting of the modem, speed, packet loss, latency problems, and the un-bonding of channels.

In a self troubleshooting effort to try to obtain better connectivity / more wiggle room, 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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