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EricCooper's avatar
EricCooper
Tutor
May 27, 2021

CM1200 Modem Upstream Light Flashing

The upstream light on my CM1200 is continously blinkinking.  I do have internet service, but the modem admin console says that the upstream bonded channels only have partial service and show only 1 channel locked.

 

There are lots of errors in the log. The below is repeated over and over.

 

Is this a modem problem or is this Comcast?


Thanks for any help

Eric

 

Thu May 27 08:10:05 2021Critical (3)No Ranging Response received - T3 time-out;CM-MAC=28:80:88:af:7e:40;CMTS-MAC=00:01:5c:b2:9c:67;CM-QOS=1.1;CM-VER=3.1;
Thu May 27 08:09:14 2021Critical (3)16 consecutive T3 timeouts while trying to range on upstream channel 3;CM-MAC=28:80:88:af:7e:40;CMTS-MAC=00:01:5c:b2:9c:67;CM-QOS=1.1;CM-VER=3.1;

1 Reply

  • plemans's avatar
    plemans
    Guru - Experienced User
    May 27, 2021

    do you have a screen snip of the cable connections page? (all of it)

    Also, if you have any splitters, amplifiers, or signal attenuators in the coax line, remove them. 

    check the line for kinks, damage, old/bad/corroded/cheap cables and connectors. replace them if you do. 

    preferably, move the modem to right where the coax enters the home.