Contributor
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16 Messages
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 |
Accepted Solution
croberts77
Contributor
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16 Messages
5 years ago
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.
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croberts77
Contributor
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16 Messages
5 years ago
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.
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EG
Expert
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111.5K Messages
5 years ago
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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EG
Expert
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111.5K Messages
5 years ago
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
Contributor
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16 Messages
5 years ago
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:
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.
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croberts77
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16 Messages
5 years ago
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.
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EG
Expert
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111.5K Messages
5 years ago
O/k "bah"... Good luck again..................
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croberts77
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16 Messages
5 years ago
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
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EG
Expert
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111.5K Messages
5 years ago
Glad that you got it straightened out ! Hope things hold up for you ! Now closing this thread.
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