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Connection constantly stutters and drops and the modem log is full of errors
Hi all -
I have xfinity internet (obviously) with 400mb down. Over the past few months, I've experienced increasingly erratic connectivity, making it almost impossible to play a simple youtube video without it stopping and giving you the old buffering circle every 15-30 seconds.
I have an Arris MB8611 modem that I bought approximately one year ago and I don't believe that's the issue. I do have my own router, but I disconnected it and went straight to the modem from my desktop to make sure that wasn't the issue. Of course I did the usual (reboot modem, check all cables, etc), but the issues remained.
My only thought (and this is pure speculation) is that maybe it's the drop coming to the house. My connection goes from the tap (up on a pole, not in a pedestal) into a grounding block on the outside of the house, and then another cable from that straight to the modem. Essentially it's drop-->grounding block coupler---> cable modem. No splitters or other devices on the line (I have a basic xfinity TV service but it's not hooked up and the little box is in a drawer). Although I replaced the cable from the grounding block to the modem a few years ago, the drop is pretty old. We bought the house in 2014 and the old woman who lived here for many years had satellite TV and no cable services. I'm not sure how old the drop is, but I'm guessing it has to be at least 20 years, and probably much older than that. It was hanging disconnected for who knows how long. Again though, this is pure speculation on my part.
Here's my event log (I did a factory reset on my modem just yesterday so this is as far back as the log goes):
| 18:12:05 Sun Jul 2 2023 |
Critical (3) | SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=xx:xx:xx:xx:xx:xx;CMTS-MAC=xx:xx:xx:xx:xx:xx;CM-QOS=1.1;CM-VER=3.1; | |||
| Time Not Established | Critical (3) | SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=xx:xx:xx:xx:xx:xx;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1; | |||
| Time Not Established | Critical (3) | No Ranging Response received - T3 time-out;CM-MAC=xx:xx:xx:xx:xx:xx;CMTS-MAC=xx:xx:xx:xx:xx:xx;CM-QOS=1.1;CM-VER=3.1; | |||
| Time Not Established | Notice (6) | Honoring MDD; IP provisioning mode = IPv6 | |||
| 18:15:22 Sun Jul 2 2023 |
Notice (6) | DS profile assignment change. DS Chan ID: 32; Previous Profile: ; New Profile: 1 2 3.;CM-MAC=xx:xx:xx:xx:xx:xx;CMTS-MAC=xx:xx:xx:xx:xx:xx;CM-QOS=1.1;CM-VER=3.1; | |||
| 18:15:22 Sun Jul 2 2023 |
Critical (3) | SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=xx:xx:xx:xx:xx:xx;CMTS-MAC=xx:xx:xx:xx:xx:xx;CM-QOS=1.1;CM-VER=3.1; | |||
| 18:15:30 Sun Jul 2 2023 |
Critical (3) | No Ranging Response received - T3 time-out;CM-MAC=xx:xx:xx:xx:xx:xx;CMTS-MAC=xx:xx:xx:xx:xx:xx;CM-QOS=1.1;CM-VER=3.1; | |||
| 18:20:33 Sun Jul 2 2023 |
Notice (6) | CM-STATUS message sent. Event Type Code: 24; Chan ID: 193; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: 0.;CM-MAC=xx:xx:xx:xx:xx:xx;CMTS-MAC=xx:xx:xx:xx:xx:xx;CM-QOS=1.1;CM-VER=3.1; | |||
| 20:17:26 Sun Jul 2 2023 |
Critical (3) | Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=xx:xx:xx:xx:xx:xx;CMTS-MAC=xx:xx:xx:xx:xx:xx;CM-QOS=1.1;CM-VER=3.1; | |||
| 23:14:04 Sun Jul 2 2023 |
Notice (6) | CM-STATUS message sent. Event Type Code: 16; Chan ID: 193; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: 2.;CM-MAC=xx:xx:xx:xx:xx:xx;CMTS-MAC=xx:xx:xx:xx:xx:xx;CM-QOS=1.1;CM-VER=3.1; | |||
| 23:19:42 Sun Jul 2 2023 |
Notice (6) | CM-STATUS message sent. Event Type Code: 24; Chan ID: 193; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: 0 2.;CM-MAC=xx:xx:xx:xx:xx:xx;CMTS-MAC=xx:xx:xx:xx:xx:xx;CM-QOS=1.1;CM-VER=3.1; | |||
| 10:13:10 Mon Jul 3 2023 |
Critical (3) | Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=xx:xx:xx:xx:xx:xx;CMTS-MAC=xx:xx:xx:xx:xx:xx;CM-QOS=1.1;CM-VER=3.1; |
Accepted Solution
EG
Expert
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110.2K Messages
2 years ago
Yes, thanks. OK so even though the signal status values looked OK at that snapshot in time, the error log entries confirm that something is going on. Perhaps there is noise ingress into the line(s) / an upstream channel / return path impairment somewhere.
There are other signal stat values 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 (The Digital Care Team) who are available to these boards. They will be able to poll the CMTS (Cable Modem Termination System) to check for any real-time degradation and / or error reports, see your node / cable plant, and modem health, and see whether or not everything is in the green zone. They can also see a history plot for the modem and poll the CMTS for those upstream receive signal stats. You should get a reply here in your topic. Good luck !
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EG
Expert
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110.2K Messages
2 years ago
What do the modem's signal stats look like ? Try getting them here; http://192.168.100.1
Please copy all of the text in its entirety of the *Downstream Power Levels*, the *SNR's* (Signal to Noise Ratios), and the *Upstream Power Level* numbers and paste them into your next post.
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jbroge01
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3 Messages
2 years ago
Thank you for your reply. Is this what you're looking for?
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jbroge01
Visitor
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3 Messages
2 years ago
Thank you so much for your help.
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EG
Expert
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110.2K Messages
2 years ago
@jbroge01
You're quite welcome !
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