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Modem disconnects SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing
Hello, been having issues with frequent modem disconnects. Started about a month ago. It would disconnect about 1-2 times a week. Since last week its now happening multiple times a day. I called tech support on April 2nd and they said the fixed the issue. They said it was a network clutter issue and "cleaned the congestion and clutter in the network". They had me restart my modem. It worked well for the rest of the day and most of today. But today (April 3rd) at 7:43pm PDT the modem disconnected again.
I logged in and grabbed the logs from the cable modem (removed mac address):
| Time | Priority | Description |
| Mon Apr 03 18:52:35 2023 | Critical (3) | No Ranging Response received - T3 time-out;;CM-QOS=1.0;CM-VER=3.0; |
| Mon Apr 03 18:52:35 2023 | Warning (5) | B-INIT-RNG Failure - Retries exceeded;;CM-QOS=1.0;CM-VER=3.0; |
| Mon Apr 03 18:52:39 2023 | Notice (6) | Honoring MDD; IP provisioning mode = IPv6 |
| Mon Apr 03 18:53:19 2023 | Critical (3) | DHCP failed - DHCP Solicit sent, No DHCP Advertise received;;CM-QOS=1.0;CM-VER=3.0; |
| Mon Apr 03 18:53:20 2023 | Critical (3) | SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;;CM-QOS=1.0;CM-VER=3.0; |
| Mon Apr 03 18:53:27 2023 | Warning (5) | Lost MDD Timeout;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0; |
| Mon Apr 03 18:53:37 2023 | Critical (3) | No UCDs Received - Timeout;;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0; |
| Mon Apr 03 18:53:40 2023 | Critical (3) | SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0; |
| Mon Apr 03 18:53:47 2023 | Warning (5) | Lost MDD Timeout;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0; |
| Mon Apr 03 18:53:57 2023 | Critical (3) | No UCDs Received - Timeout;;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0; |
| Mon Apr 03 18:54:00 2023 | Critical (3) | SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0; |
| Mon Apr 03 18:54:07 2023 | Warning (5) | Lost MDD Timeout;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0; |
| Mon Apr 03 18:54:17 2023 | Critical (3) | No UCDs Received - Timeout;;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0; |
| Mon Apr 03 18:54:20 2023 | Critical (3) | SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0; |
| Mon Apr 03 18:54:27 2023 | Warning (5) | Lost MDD Timeout;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0; |
| Mon Apr 03 18:54:37 2023 | Critical (3) | No UCDs Received - Timeout;;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0; |
| Mon Apr 03 18:54:40 2023 | Critical (3) | SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0; |
| Mon Apr 03 18:54:47 2023 | Warning (5) | Lost MDD Timeout;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0; |
| Mon Apr 03 18:54:57 2023 | Critical (3) | No UCDs Received - Timeout;;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0; |
| Mon Apr 03 18:55:08 2023 | Notice (6) | Honoring MDD; IP provisioning mode = IPv6 |
| Mon Apr 03 18:55:45 2023 | Critical (3) | DHCP failed - DHCP Solicit sent, No DHCP Advertise received;;CM-QOS=1.0;CM-VER=3.0; |
| Mon Apr 03 18:55:53 2023 | Warning (5) | Lost MDD Timeout;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0; |
| Mon Apr 03 18:56:03 2023 | Critical (3) | No UCDs Received - Timeout;;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0; |
| Mon Apr 03 18:56:13 2023 | Warning (5) | Lost MDD Timeout;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0; |
| Mon Apr 03 18:56:23 2023 | Critical (3) | No UCDs Received - Timeout;;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0; |
| Mon Apr 03 18:56:34 2023 | Warning (5) | Lost MDD Timeout;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0; |
| Mon Apr 03 18:56:44 2023 | Critical (3) | No UCDs Received - Timeout;;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0; |
| Mon Apr 03 18:58:59 2023 | Critical (3) | No Ranging Response received - T3 time-out;;CM-QOS=1.0;CM-VER=3.0; |
| Mon Apr 03 18:59:43 2023 | Notice (6) | Honoring MDD; IP provisioning mode = IPv6 |
| Mon Apr 03 19:00:07 2023 | Critical (3) | Started Unicast Maintenance Ranging - No Response received - T3 time-out;;CM-QOS=1.1;CM-VER=3.0; |
| Mon Apr 03 19:01:13 2023 | Critical (3) | Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;;CM-QOS=1.1;CM-VER=3.0; |
| Mon Apr 03 19:01:23 2023 | Notice (6) | Honoring MDD; IP provisioning mode = IPv6 |
Any help would be greatly appreciated.
Thanks
Accepted Solution
BruceW
Gold Problem Solver
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26.3K Messages
2 years ago
The downstream power levels and SNR are good. The error counts seem high, although I can't really say since the "uptime" isn't shown. On the upstream side the power levels are out of spec (too high). These readings suggest, as stated above, a problem with the modem's connection to Comcast's network. If you can't find and fix it you'll need to have a premise tech out to take care of it.
Please be aware that there are 2 kinds of responses in this Forum: Replies and Comments. When you Comment on a post by scrolling down to "Comment on this post here...", I am notified of your response. But if you select Reply, I am NOT notified and may not be aware of your response.
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BruceW
Gold Problem Solver
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26.3K Messages
2 years ago
That's gibberish.
The event log indicates the device is having trouble connecting to Comcast's network, but does not help us understand why. Network problems are often due to poor coax connections or damaged coax cable, usually in or near your home. Running the cable through a surge protector, a defective splitter, or too many splitters can cause signal problems as well. If there is an amplifier in the line make sure it's getting power.
If you want to troubleshoot this yourself, please see Internet Troubleshooting Tips. If you still need help, please post the following information from your modem or gateway (from http://192.168.100.1):
If you can't find the problem or you'd rather have Comcast take care of it and an employee does not respond to your message here, call them at the phone number on your bill or 1-800-Comcast, or use one of the options on https://www.xfinity.com/support/contact-us/. It's not likely they can fix the problem remotely. If not, insist they send a tech out to identify the cause and correct it.
If the tech finds bad coax, splitters, amplifiers, or connections in your home (even if Comcast originally supplied them) you'll probably have to pay for the visit ($70-$100) unless you have their Service Protection Plan ( https://www.xfinity.com/support/articles/service-protection-plan, closed to customers that don't already have it). If the trouble is due to a faulty Comcast rental device or anything outside your home you shouldn't be charged.
Please be aware that there are 2 kinds of responses in this Forum: Replies and Comments. When you Comment on a post by scrolling down to "Comment on this post here...", I am notified of your response. But if you select Reply, I am NOT notified and may not be aware of your response.
(edited)
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user_41d1b3
Visitor
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3 Messages
2 years ago
Thanks for the reply Bruce! I really appreciate it. I checked the coax cables and they look good as far as I can see. Below are the downstream and upstream data I got from my modem:
Downstream:
Upstream:
Today I didn't notice any disconnects. But that could just be lucky roll of the dice.
Thanks for the help!
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user_41d1b3
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3 Messages
2 years ago
Thanks for looking at the logs and all the info Bruce! I reached out to Xfinity and they came out a week ago. It turns out it was a splitter issue. Took out the splitter and connection has been stable! No disconnects.
Thanks again!
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