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Internet cutting off multiple times daily - T2, T3, Failed to acquire QAM/QPSK symbol timing
Help! My Xfinity internet has been cutting of very often these days. Today has been really bad. I had to reset my modem multiple times already, and after every reset, it only works fine for a few minutes before the internet is cut off again. Wi-fi connection to the router/modem is fine, only the internet is bad. I am using Netgear C7800 modem/router.
Here are some event logs I got from the netgear modem:
Warning (5) MDD message timeout
Critical (3) No Maintenance Broadcasts for Ranging opportunities received - T2 time-out
Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing
Critical (3) No Ranging Response received - T3 time-out
Critical (3) No Maintenance Broadcasts for Ranging opportunities received - T2 time-out
Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing
Critical (3) No Ranging Response received - T3
BruceW
Gold Problem Solver
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25.5K Messages
4 years ago
Please post your gateway's signal information, especially downstream power levels and SNR, upstream power levels, and the complete error log with date and time info. Also see Internet Troubleshooting Tips.
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hendolim
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3 Messages
4 years ago
@BruceW Previously I was resetting the modem physically. After resetting the gateway from xfinity web page, it seems to be okay now (have been running for 1hr uninterrupted).
Here is the status currently:
And here are the complete logs when the internet was down:
Time Priority Description
2020-07-16, 11:29:22 Warning (5) MDD message timeout;CM-MAC=28:80:88:ab:de:28;CMTS-MAC=00:01:5c:b6:20:7a;CM-QOS=1.1;CM-VER=3.1;
2020-07-16, 11:29:16 Critical (3) No Maintenance Broadcasts for Ranging opportunities received - T2 time-out;CM-MAC=28:80:88:ab:de:28;CMTS-MAC=00:01:5c:b6:20:7a;CM-QOS=1.1;CM-VER=3.1;
2020-07-16, 11:29:07 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;CM-MAC=28:80:88:ab:de:28;CMTS-MAC=00:01:5c:b6:20:7a;CM-QOS=1.1;CM-VER=3.1;
2020-07-16, 11:28:38 Critical (3) No Ranging Response received - T3 time-out;CM-MAC=28:80:88:ab:de:28;CMTS-MAC=00:01:5c:b6:20:7a;CM-QOS=1.1;CM-VER=3.1;
2020-07-16, 11:28:32 Critical (3) No Maintenance Broadcasts for Ranging opportunities received - T2 time-out;CM-MAC=28:80:88:ab:de:28;CMTS-MAC=00:01:5c:b6:20:7a;CM-QOS=1.1;CM-VER=3.1;
2020-07-16, 11:28:24 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;CM-MAC=28:80:88:ab:de:28;CMTS-MAC=00:01:5c:b6:20:7a;CM-QOS=1.1;CM-VER=3.1;
2020-07-16, 11:28:05 Critical (3) No Ranging Response received - T3 time-out;CM-MAC=28:80:88:ab:de:28;CMTS-MAC=00:01:5c:b6:20:7a;CM-QOS=1.1;CM-VER=3.1;
2020-07-16, 11:27:58 Warning (5) MDD message timeout;CM-MAC=28:80:88:ab:de:28;CMTS-MAC=00:01:5c:b6:20:7a;CM-QOS=1.1;CM-VER=3.1;
2020-07-16, 11:27:56 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;CM-MAC=28:80:88:ab:de:28;CMTS-MAC=00:01:5c:b6:20:7a;CM-QOS=1.1;CM-VER=3.1;
2020-07-16, 11:27:56 Warning (5) MDD message timeout;CM-MAC=28:80:88:ab:de:28;CMTS-MAC=00:01:5c:b6:20:7a;CM-QOS=1.1;CM-VER=3.1;
2020-07-16, 11:27:53 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;CM-MAC=28:80:88:ab:de:28;CMTS-MAC=00:01:5c:b6:20:7a;CM-QOS=1.1;CM-VER=3.1;
2020-07-16, 11:21:02 Critical (3) No Ranging Response received - T3
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hendolim
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3 Messages
4 years ago
It just went down again... I noticed the upstream and online lights on the modem was off this time.
Here is the status when that happened:
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BruceW
Gold Problem Solver
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25.5K Messages
4 years ago
The signal info you've posted looks OK, but obviously there's a problem somewhere.
If you can't find the problem call Comcast 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/. 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 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.
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CCAndrew
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25.9K Messages
4 years ago
I’m not sure if you noticed but the first pic had no levels after downstream channel 16 but were there In the second. As suggested, start with a tech visit.
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