TekSavvy → [Cable] Strange modem behaviour

I have a Tomson DCM 476 cable modem that, for no reason at all
goes from 5 blue lights illumminated on the front panel to a flashing
state of the first blue light ( left hand side next to the yellow power
light) quite occasionally. I have no idea what it means but when I
check the modems error logs like this:

Response Thu Apr 24 06:19:56 2014 Critical (3) SYNC Timing Synchronization failure - Failed to receive MAC S...
Thu Apr 24 06:15:02 2014 Critical (3) SYNC Timing Synchronization failure - Failed to receive MAC S...
Wed Apr 23 08:40:39 2014 Critical (3) No Ranging Response received - T3 time-out;CM-MAC=c4:27:95:73...

Any ideas what these entries mean?

Yatzee

The modem is losing the RF signal. Either the signal IS still there and the modem is failing, or more likely there is a loose connection/bad cable somewhere. Or the signal you are getting is fluctuating and is too weak or too strong.

Copy/pasta the Diagnostics page when the modem is working, and again when its flashing if you can catch it.

Reseat /replace the coax from modem to the wall. Reseat it at the wall. Try a different cable outlet if you can, bypass splitters etc.

"SYNC Timing Synchronization failure - Failed to receive MAC SYNC frame within time-out period" is what that entire thing is and is something I've rarely seen. With the modem doing what it is, that sounds like you may have borderline signal levels. Yeah, lets see all the information on the Diagnostics page like oceros mentioned to find out if the signal is the problem.

ah, i definitely stopped reading after sync failure...