Visitor
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2 Messages
Intermittent Connection Drops
Here is a sample of the logs from my cable modem showing intermittent drops of the cable connection. The connection drops every 2 - 4 hours. There are no splitters. The cable comes out of the ground to the termination box to on the house where it is connected via a grounded coupler to the house wiring. The house wiring is a single cable to the cable modem.
The periodic disconnections have greatly increased since my service was upgraded to gigabit. I had an older Arris modem that is no longer supported. I upgraded to a Motorola MB8611 with the hope that the connection interruptions would stop but the disconnections remain.
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;
03:46:42 Wed Apr 26 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;
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;
07:06:32 Wed Apr 26 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;
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 Notice (6) Honoring MDD; IP provisioning mode = IPv6
07:56:20 Wed Apr 26 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;
07:57:47 Wed Apr 26 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;
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EG
Expert
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110.5K Messages
2 years ago
This may or may not be the root cause of the problem (YMMV) but it should be addressed regardless. Also, bear in mind that we have been seeing many many posts here lately that may indicate a pattern that the 8611 is currently not playing nicely with the Comcast system / firmware problems.
The downstream power is on the low side and it may be intermittently fluctuating even lower to out-of-spec levels. The upstream power on channel #6 is a bit on the high side as well. That can cause random disconnects, spontaneous re-booting of the modem, speed, packet loss, latency problems, and the un-bonding of channels.
In an 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 5-1000 MHz, bi-directional, and no gold colored garbage from Radio Shack, Home Depot, Target, etc. Splitters should be swapped with known to be good / new ones to test.
Also check the coax cable for any damage such as cuts, nicks, abrasions, kinks, sharp bends, etc.
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.
Good luck with it !
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CCLamont
Problem Solver
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519 Messages
2 years ago
Hey @user_455a24 this is not the type of experience we want for any of our customers using our services. I appreciate all the steps you've taken to eliminate possible trouble that would contribute to the drop in service. Our amazing expert @EG mentioned a lot of helpful information too. Do you see any damage to the line itself?
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EG
Expert
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110.5K Messages
2 years ago
@user_455a24 @XfinityLamont @XfinityVianney
Please circle back here and post any possible solutions for the issue here in the open forums so that all readers here may benefit from the exchange / info. This is in keeping with the spirit for which these public help forums were originally intended. Thank you.
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