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mathjk's avatar
New Contributor
3 years ago

OFDM Channel not locked - Downstream light consistently blinking now

Exact same was posted a few months ago but the thread is locked and it failed to highlight a tangible solution.

We have the same Netgear Modem CM1200, the same symptoms of constantly blinking light, and massive amounts of disconnections and lost packets.

Technicians tell the same story; our signal looks good therefore it must be the Modem. The last technician recommended we get a firmware update for the modem but that cannot be done because modem updates should be pushed by the ISP. We cannot update our firmware.

Our logs suggest the issue is on Cox side. DOCSIS 3.1 not working?

Mon Dec 13 17:06:43 2021 Notice (6) CM-STATUS message sent. Event Type Code: 16; Chan ID: 159; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: 3.;CM-MAC=08:36:c9:a3:b9:e0;CMTS-MAC=00:29:c2:00:57:92;CM-QOS=1.1;CM-VER=3.1;
Mon Dec 13 17:06:09 2021 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=08:36:c9:a3:b9:e0;CMTS-MAC=00:29:c2:00:57:92;CM-QOS=1.1;CM-VER=3.1;

This has been going on for several months now - and we keep changing hardware, cables, splitters, router, modem - yet the problem persists.

As a side not, we are part of the legacy Cable America folks that were acquired by Cox. Time to refresh the infrastructure?


2 Replies

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  • BenS1's avatar
    Former Moderator
    Hi @Mathjk
    I completely understand the frustration of having an inconsistent internet signal especially when it goes unresolved for months. I have checked your network and there are no outstanding issues in your area. Are there any splitters or amplifiers that are connected to the coaxial that is screwed into the back of your modem?

    Ben S.
    Cox Support Forums Moderator
    • mathjk's avatar
      New Contributor

      Sorry for the late reply. After numerous phone calls to Netgear pleading to update the firmware we had no other choice but to go with Panoramic Wi-Fi. Our problems went away instantly when we installed the new device. The downside is that now I have to pay a monthly rental and I own a $200 brick. Also, port forwarding doesn't work on the Panoramic Wi-Fi.