Forum Discussion

mehfisto's avatar
New Contributor
4 years ago

T3/T4 timeouts, packet loss, latency


I've been dealing wiht inconsistent internet performance and degrading service for a few weeks. All our devices will slowly stop working, and then mgically recover. After plugging some d vices directly into the cable modem, we are seeing packet loss with pings on a semi-regular basis, or significantly increased latencies upwards of 200-500ms when the normal response is 10ms.

The modem pops these errors during the time periods when we experience the latency (i redacted mac addresses). While trying to write this post it took down our service for a bit. The packet loss will be 5-20 packets during a continous ping of targets like cloudflare DNS ( or google ( while not the most relaible targets, the loss experienced, plus it coinciding with service degredation and the alignment with the t3 events in the modem indicate an upstream problem from our cable modem.

Would someone please help with this issue?

2020-08-03, 17:19:48

Critical (3)

Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=3c:37:86:xx:xx:xx;CMTS-MAC=00:7e:95:xx:xx:xx;CM-QOS=1.1;CM-VER=3.1;

6 Replies

  • Viole's avatar
    New Contributor III

    I also have the same issue along with dynamic range windows violation. I called earlier, and they said it was a modem problem so I got a new modem, but the issue is still present. 

    • mehfisto's avatar
      New Contributor

      Thanks for the data point. I'll be sure to push back on a modem replacement. I'm also seeing power/signal fluctuation messages, are you as well?

      • ChrisL's avatar
        Former Moderator
        If you're seeing signal related events in the modem logs I'd also suggest trying to bypass any cable splitters or testing the modem at a different cable outlet. If none of that helps with your service concerns it may be necessary to see about scheduling a technician to come troubleshoot further.

  • dnktillman1's avatar
    New Contributor

    Having same issue.  This has been happening for over a year now.  I thought it was my modem that was a few years old, but the modem has been replaced and it is worse now.  At least once per hour it goes down and comes back after a few mins.  

    • Allan's avatar
      @Dnktillman1 We may need to send a tech out since replacing the modem did not resolve the issue. Please send us an email with your full name, address, and a brief description of the concern to -Allan, Cox Support Forums Moderator.