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Frequent connection drops

croberts77
Frequent Visitor

Frequent connection drops

Over the past month or so, I've been noticing my connection drop briefly (usually just a few minutes).  Below is my cable modem event log from yesterday (as well as my current status).  Looks like there were 3 cut outs.

 

I've had a very solid connection prior to this.  They (xfinity) did recently replace the cable from the box to my house (Not sure why...they said they suspected a signal leak....I did not call them).  Ever since then, I've experienced this flakiness.  I have tightned all the connections inside my house and I even replaced the splitter (went from a 4 way to a 3-way since we only need 3 lines). 

 

I'm noticing that I often wind-up with just one upstream channel (with power level of 57.0!), but if I power cycle the modem, I tend to get 3 or 4 with power levels all in the low to mid 40s.

 

Anyone here have any insight on things I might be able to try?

 

 

Sun Jun 14 12:09:36 2020 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=78:96:84:e4:66:44;CMTS-MAC=00:01:5c:8f:86:47;CM-QOS=1.1;CM-VER=3.0;
Sun Jun 14 12:13:56 2020 Critical (3) Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=78:96:84:e4:66:44;CMTS-MAC=00:01:5c:8f:86:47;CM-QOS=1.1;CM-VER=3.0;
Sun Jun 14 17:19:17 2020 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=78:96:84:e4:66:44;CMTS-MAC=00:01:5c:8f:86:47;CM-QOS=1.1;CM-VER=3.0;
Sun Jun 14 17:23:37 2020 Critical (3) Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=78:96:84:e4:66:44;CMTS-MAC=00:01:5c:8f:86:47;CM-QOS=1.1;CM-VER=3.0;
Sun Jun 14 17:28:42 2020 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=78:96:84:e4:66:44;CMTS-MAC=00:01:5c:8f:86:47;CM-QOS=1.1;CM-VER=3.0;
Sun Jun 14 17:33:03 2020 Critical (3) Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=78:96:84:e4:66:44;CMTS-MAC=00:01:5c:8f:86:47;CM-QOS=1.1;CM-VER=3.0;
Time Not Established Notice (6) Honoring MDD; IP provisioning mode = IPv6

 

 

Channel Lock Status Modulation Channel ID Frequency Power SNR Corrected Uncorrectables
1 Locked QAM256 38 429000000 Hz -5.2 dBmV 40.3 dB 1160 57
2 Locked QAM256 39 435000000 Hz -4.7 dBmV 40.4 dB 1226 58
3 Locked QAM256 40 441000000 Hz -4.5 dBmV 40.4 dB 1201 144
4 Locked QAM256 41 447000000 Hz -4.6 dBmV 40.3 dB 1105 37
5 Locked QAM256 29 453000000 Hz -4.9 dBmV 40.3 dB 1166 52
6 Locked QAM256 34 459000000 Hz -4.9 dBmV 40.3 dB 1164 52
7 Locked QAM256 35 465000000 Hz -3.7 dBmV 40.7 dB 990 98
8 Locked QAM256 36 471000000 Hz -3.6 dBmV 39.7 dB 991 105
9 Locked QAM256 1 477000000 Hz -4.1 dBmV 40.2 dB 1057 54
10 Locked QAM256 2 483000000 Hz -4.2 dBmV 36.3 dB 1201 56
11 Locked QAM256 3 489000000 Hz -3.3 dBmV 40.1 dB 1031 105
12 Locked QAM256 4 495000000 Hz -3.3 dBmV 40.0 dB 1064 118
13 Locked QAM256 5 507000000 Hz -3.9 dBmV 39.5 dB 933 46
14 Locked QAM256 6 513000000 Hz -3.6 dBmV 40.6 dB 941 71
15 Locked QAM256 7 519000000 Hz -3.0 dBmV 40.8 dB 1279 50
16 Locked QAM256 8 525000000 Hz -3.5 dBmV 40.4 dB 879 56

 

 
Upstream Bonded Channels
Channel Lock Status US Channel Type Channel ID Symbol Rate Frequency Power
1 Locked ATDMA 4 5120 Ksym/sec 16600000 Hz 57.0 dBmV
croberts77
Frequent Visitor

Re: Frequent connection drops

fwiw, I just power cycled the modem and here's my new status:  back to 4 upstream channels locked with nice (imho) upstream power levels.  At some point today, I suspect things will go south.  I can't find the pattern/reason though.

 

Channel Lock Status Modulation Channel ID Frequency Power SNR Corrected Uncorrectables
1 Locked QAM256 17 579000000 Hz -3.9 dBmV 40.1 dB 0 0
2 Locked QAM256 18 585000000 Hz -4.1 dBmV 40.0 dB 0 0
3 Locked QAM256 19 591000000 Hz -4.0 dBmV 39.9 dB 0 0
4 Locked QAM256 20 597000000 Hz -4.0 dBmV 39.9 dB 0 0
5 Locked QAM256 21 603000000 Hz -4.2 dBmV 39.6 dB 0 0
6 Locked QAM256 22 609000000 Hz -4.4 dBmV 39.8 dB 0 0
7 Locked QAM256 23 615000000 Hz -4.1 dBmV 39.8 dB 0 0
8 Locked QAM256 24 621000000 Hz -4.4 dBmV 39.6 dB 0 0
9 Locked QAM256 25 627000000 Hz -4.6 dBmV 39.5 dB 0 0
10 Locked QAM256 26 633000000 Hz -4.7 dBmV 39.5 dB 0 0
11 Locked QAM256 27 639000000 Hz -4.6 dBmV 39.5 dB 0 0
12 Locked QAM256 28 645000000 Hz -5.3 dBmV 39.4 dB 0 0
13 Locked QAM256 30 651000000 Hz -5.7 dBmV 39.2 dB 0 0
14 Locked QAM256 31 657000000 Hz -5.5 dBmV 39.3 dB 0 0
15 Locked QAM256 32 663000000 Hz -5.1 dBmV 39.4 dB 0 0
16 Locked QAM256 33 669000000 Hz -4.0 dBmV 39.7 dB 0 0

 

 
Upstream Bonded Channels
Channel Lock Status US Channel Type Channel ID Symbol Rate Frequency Power
1 Locked ATDMA 4 5120 Ksym/sec 16600000 Hz 39.8 dBmV
2 Locked ATDMA 1 5120 Ksym/sec 35800000 Hz 42.5 dBmV
3 Locked ATDMA 2 5120 Ksym/sec 29400000 Hz 42.0 dBmV
4 Locked ATDMA 3 5120 Ksym/sec 23000000 Hz 40.8 dBmV
EG
Expert

Re: Frequent connection drops

At 57 dB the upstream power is way out of spec. That can cause random disconnects, spontaneous re-booting of the modem, speed, packet loss, latency problems, and the un-bonding of the channels. And it should not be intermittently fluctuating that high either. Something is going on with the connection / lines hardware somewhere.

 

Here's some stuff to try if any of it even applies. The problem is perhaps beyond your premises. You'll probably need to get the techs re-involved.

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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croberts77
Frequent Visitor

Re: Frequent connection drops

Thanks for your reply.

 

Yeah, 57 is way out of spec for sure.  Anytime I've caught my modem in that state, I manually powercycle it and it seems to be ok again.  My hunch is that it will eventually get to the disconnect hiccup at some point when I don't intervene.  Seems to do that 3-5 times a day recently.

 

After my reboot this morning, my upstream numbers look like this:

 

1 Locked ATDMA 4 5120 Ksym/sec 16600000 Hz 39.8 dBmV
2 Locked ATDMA 1 5120 Ksym/sec 35800000 Hz 42.5 dBmV
3 Locked ATDMA 2 5120 Ksym/sec 29400000 Hz 42.0 dBmV
4 Locked ATDMA 3 5120 Ksym/sec 23000000 Hz 40.8 dBmV

 

I'm tempted to set up a script that will monitor the numbers reported in the status page so I can find out exactly when things start to go wacky so maybe I can find a pattern.  Of course, there is a chance that this is indeed outside of my influence.  I'd love to work with somone from Comcast to do some digging on what they're seeing on their end, but not sure I feel like going through the hour of scripted rubbish before getting to the more interesting stuff.

EG
Expert

Re: Frequent connection drops

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 !



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croberts77
Frequent Visitor

Re: Frequent connection drops

Bah, 2 long chats with Xfinity support today and I'm no closer to a solution than when the day started.  One suggested that the problem might be my cable modem, but I'm not sold on that answer.

1)  When I have an outage, my TV box also says that it can't connect to the internet

2) The modem has performed flawlessly for years and the issues only started recently after they replaced the line from my box to my house (they said they were trying to fix a "leak" in my neighborhood).

 

They didn't even think about sending a tech out.  No idea what I can do/ask for next.

 

EG
Expert

Re: Frequent connection drops

O/k "bah"... Good luck again..................



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croberts77
Frequent Visitor

Re: Frequent connection drops

Ok, I almost had to eat crow.  Yesterday, I had a perfect connection day....and all day today.  No drops and there were only like 9 "correctables" in my logs.  Then came the last hour.  At least 3 disconnects.  Although my modem status shows good signal levels for everything now.

 

Is there any way that noise can somehow be getting in there intermittently and causing the problems?  All the events in my event log seem to be T3 related.  What's the best way I can monitor this or get someone's attention to take a closer look?  I'm in a rather rural area and my one neighbor says that they haven't noticed any issues, but they are not particularly heavy tech users, so they might just not realize that they are also seeing intermittent drops.

 

Here's my current status and event log

 

Channel Lock Status Modulation Channel ID Frequency Power SNR Corrected Uncorrectables
1 Locked QAM256 38 429000000 Hz -6.0 dBmV 40.3 dB 7 26
2 Locked QAM256 39 435000000 Hz -5.8 dBmV 40.3 dB 0 0
3 Locked QAM256 40 441000000 Hz -5.6 dBmV 40.3 dB 0 0
4 Locked QAM256 41 447000000 Hz -5.5 dBmV 40.3 dB 0 0
5 Locked QAM256 29 453000000 Hz -5.4 dBmV 40.3 dB 0 0
6 Locked QAM256 34 459000000 Hz -5.1 dBmV 40.5 dB 0 0
7 Locked QAM256 35 465000000 Hz -5.0 dBmV 40.5 dB 0 0
8 Locked QAM256 36 471000000 Hz -5.2 dBmV 40.3 dB 0 0
9 Locked QAM256 1 477000000 Hz -5.0 dBmV 40.4 dB 0 0
10 Locked QAM256 2 483000000 Hz -5.2 dBmV 38.0 dB 0 0
11 Locked QAM256 3 489000000 Hz -4.7 dBmV 40.3 dB 0 0
12 Locked QAM256 4 495000000 Hz -4.8 dBmV 40.3 dB 0 0
13 Locked QAM256 5 507000000 Hz -4.5 dBmV 39.3 dB 0 0
14 Locked QAM256 6 513000000 Hz -4.8 dBmV 40.4 dB 0 0
15 Locked QAM256 7 519000000 Hz -4.9 dBmV 40.3 dB 0 0
16 Locked QAM256 8 525000000 Hz -4.6 dBmV 40.4 dB 0 0

 

 
Upstream Bonded Channels
Channel Lock Status US Channel Type Channel ID Symbol Rate Frequency Power
1 Locked ATDMA 1 5120 Ksym/sec 35800000 Hz 43.5 dBmV
2 Locked ATDMA 2 5120 Ksym/sec 29400000 Hz 43.3 dBmV
3 Locked ATDMA 3 5120 Ksym/sec 23000000 Hz 42.0 dBmV
4 Locked ATDMA 4 5120 Ksym/sec 16600000 Hz 40.5 dBmV

 

 

 

Wed Jun 17 17:06:49 2020 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=78:96:84:e4:66:44;CMTS-MAC=00:01:5c:8f:86:47;CM-QOS=1.1;CM-VER=3.0;
Wed Jun 17 17:06:49 2020 Critical (3) Unicast Maintenance Ranging attempted - No response - Retries exhausted;CM-MAC=78:96:84:e4:66:44;CMTS-MAC=00:01:5c:8f:86:47;CM-QOS=1.1;CM-VER=3.0;
Wed Jun 17 17:06:49 2020 Critical (3) 16 consecutive T3 timeouts while trying to range on upstream channel 0;CM-MAC=78:96:84:e4:66:44;CMTS-MAC=00:01:5c:8f:86:47;CM-QOS=1.1;CM-VER=3.0;
Wed Jun 17 17:06:57 2020 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=78:96:84:e4:66:44;CMTS-MAC=00:01:5c:8f:86:47;CM-QOS=1.1;CM-VER=3.0;
Wed Jun 17 17:06:57 2020 Critical (3) Unicast Maintenance Ranging attempted - No response - Retries exhausted;CM-MAC=78:96:84:e4:66:44;CMTS-MAC=00:01:5c:8f:86:47;CM-QOS=1.1;CM-VER=3.0;
Wed Jun 17 17:06:57 2020 Critical (3) 16 consecutive T3 timeouts while trying to range on upstream channel 3;CM-MAC=78:96:84:e4:66:44;CMTS-MAC=00:01:5c:8f:86:47;CM-QOS=1.1;CM-VER=3.0;
Wed Jun 17 17:07:45 2020 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=78:96:84:e4:66:44;CMTS-MAC=00:01:5c:8f:86:47;CM-QOS=1.1;CM-VER=3.0;
Wed Jun 17 17:07:45 2020 Critical (3) Unicast Maintenance Ranging attempted - No response - Retries exhausted;CM-MAC=78:96:84:e4:66:44;CMTS-MAC=00:01:5c:8f:86:47;CM-QOS=1.1;CM-VER=3.0;
Wed Jun 17 17:07:45 2020 Critical (3) 16 consecutive T3 timeouts while trying to range on upstream channel 2;CM-MAC=78:96:84:e4:66:44;CMTS-MAC=00:01:5c:8f:86:47;CM-QOS=1.1;CM-VER=3.0;
Wed Jun 17 17:31:01 2020 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=78:96:84:e4:66:44;CMTS-MAC=00:01:5c:8f:86:47;CM-QOS=1.1;CM-VER=3.0;
Wed Jun 17 17:35:21 2020 Critical (3) Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=78:96:84:e4:66:44;CMTS-MAC=00:01:5c:8f:86:47;CM-QOS=1.1;CM-VER=3.0;
Time Not Established Critical (3) No Ranging Response received - T3 time-out
Time Not Established Critical (3) No Maintenance Broadcasts for Ranging opportunities received - T2 time-out;CM-MAC=78:96:84:e4:66:44;CMTS-MAC=00:01:5c:8f:86:47;CM-QOS=1.0;CM-VER=3.0;
Time Not Established Notice (6) Honoring MDD; IP provisioning mode = IPv6
croberts77
Frequent Visitor

Re: Frequent connection drops

Ok, after 4 chats with the online help, I finally managed to get a tech out to take a look at things on Friday.  He replaced a couple things outside in the box and then also replaced the cable from my main splitter to my modem inside the house (easy, short run).  I can't say which of the fixes made the most difference, but I can say that my connection has been flawless since Friday.

 

Downstream power between -0.6 and -2.0 with SNR about 40.6.  Upstream powers of 38.5 to 41.3.  Before the fix, I was seeing flurries of correctables and uncorrectables, but since the fix, I've seen zero of each.

 

Not sure that this will help anyone else, but if you're at your wits' end and it's not a difficult or long run, maybe try running a new cable from the splitter just inside your house directly to the modem.  In my case, the cable in the wall was slightly lower quality and the connectors used were typical contractor-grade rubbish.  It is definitely possible that the run inside my house was responsible for a big part of my issues.

EG
Expert

Re: Frequent connection drops

Glad that you got it straightened out ! Hope things hold up for you ! Now closing this thread.



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I am a Customer Expert volunteering my time to help other customers here in the Forums.
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