Visitor
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10 Messages
Internet Disconnects and Unusual Router Logs
Hello,
Since about mid-January we've been having a new spate of daily internet disconnects. This is about six months after a technician came out, replaced the pole drop into the house, and everything has been working great. All modem lights go out, and then everything comes up about a minute later. These are the corresponding event logs:
| Time | Priority | Description |
| 1970-1-1, 00:00:51 | Notice (6) | Honoring MDD; IP provisioning mode = IPv6 |
| 1970-1-1, 00:00:41 | Notice (6) | WiFi Interface [wl1] set to Channel 153 (Side-Band Channel:N/A) - Reason:INIT |
| 1970-1-1, 00:00:41 | Notice (6) | WiFi Interface [wl0] set to Channel 11 (Side-Band Channel:N/A) - Reason:INIT |
| 1970-1-1, 00:00:37 | Critical (3) | SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0; |
| 1970-1-1, 00:00:44 | Critical (3) | No Ranging Response received - T3 time-out;CM-MAC=;CMTS-MAC=;CM-QOS=1.0;CM-VER=3.0; |
| 1970-1-1, 00:00:37 | Critical (3) | SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0; |
| 1970-1-1, 00:00:44 | Critical (3) | No Ranging Response received - T3 time-out;CM-MAC=;CMTS-MAC=;CM-QOS=1.0;CM-VER=3.0; |
| 1970-1-1, 00:00:38 | Critical (3) | SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0; |
| 1970-1-1, 00:00:44 | Critical (3) | No Ranging Response received - T3 time-out;CM-MAC=;CMTS-MAC=;CM-QOS=1.0;CM-VER=3.0; |
| 1970-1-1, 00:00:37 | Critical (3) | SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0; |
I don't know if it's related, but the router logs also show this hundreds of times a day, repeating every few seconds, same IP and MAC address:
| Description | Count | Last Occurrence | Target | Source |
| [DHCP IP: ] to MAC address | 1 | Wed Mar 01 07:31:55 2023 | 0.0.0.0:0 | 0.0.0.0:0 |
Lastly, there are these other logs that only -seem- to show up when I have our exercise bike connected*. I also don't know if these are related, or if they ever correspond to the event logs above since the time and date on those is obviously wrong. I've removed the IPs here, but they are also wildly different from anything else connected to our network. Not sure if that's relevant.
*for a brief moment a few days ago, the exercise bike appeared in the attached devices list with one of these different IP addresses. I blocked it out of curiosity. Haven't had these two logs appear since, and the bike showed its normal address after that (I really don't know how any of this works if that wasn't obvious). I unblocked it yesterday, and this morning the screen and android OS woke itself up, and when I checked the router logs a half hour later after an internet disconnect, found these.
| [DoS attack: Ping Of Death] from , port 0 | 1 | Wed Mar 01 06:51:57 2023 |
| [DoS attack: Teardrop or derivative] from , port 0 | 1 | Wed Mar 01 06:51:45 2023 |
Lastly, here's our upstream/downstream info.
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Any help from the community or lurking Xfinity peeps would be wonderful. This is all from a Netgear Nighthawk C7000v2 running firmware V1.03.08, and honestly I'm at the point of just wanting to replace it, but I don't want to waste money if that isn't the root problem.
Thank you so much in advance.
CCTimothyA
Problem Solver
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785 Messages
2 years ago
@user_ac6699 Thank you for reaching out and bringing this to our attention. I can understand how this would be frustrating, and We would be more than happy to look into this for you. Do you notice this happening during certain times of the day or is it random?
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user_ac6699
Visitor
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10 Messages
2 years ago
It seems fairly random. Yesterday morning about a half-hour before I posted this it happened, and then again late last night while playing video games. Thank you for your assistance!
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zandor60657
Contributor
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204 Messages
2 years ago
Your signal to noise ratio is in spec though it could be better. Your downstream power levels are on the high side and some of them are out of spec but only a little out of spec. That sort of situation is likely to cause an occasional modem reset. It'll work ok most of the time until... oops, reset. Resetting your modem if you drop offline is likely to fix the problem temporarily, but it'll just happen again. Your line is out of spec according to Comcast. Max downstream power is +10dBmv for a cable modem and you're over that on some channels, so your connection is out of spec per Comcast.
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