I am not sure if I should make my own thread but I am having a very similar problem it would seem. My modem resets itself randomly and sometimes does not reconnect and will not until it is power cycled. At first, all of the lights go out on the modem except the power light and then it either reconnects normally, or gets stuck with the "receive" light green, the "send" light blue and the "online" light off. This problem happens quite often, sometimes several times an hour.
I have contacted Comcast before but they only reset the router remotely which did not help. I have not had a tech come out yet.
Here is the specs on my modem and connection as well as some recent error logs (sorry for the formatting).
DownstreamBonding Channel Value Channel ID 1 5 6 7 Frequency 627000000 Hz 651000000 Hz 657000000 Hz 663000000 Hz Signal/Noise Ratio 36 dB 36 dB 35 dB 35 dB Downstream Modulation QAM256 QAM256 QAM256 QAM256 Power Level 8 dBmV 8 dBmV 8 dBmV 7 dBmV
UpstreamBonding Channel Value Channel ID 4 3 Frequency 34800000 Hz 27900000 Hz Ranging Service ID 3041 3041 Symbol Rate 5.120 Msym/sec 2.560 Msym/sec Power Level 44 dBmV 53 dBmV Upstream Modulation  QPSK  QPSK  64QAM  16QAM  64QAM Ranging Status Success Success
Oct 21 2012 22:05:08
No Ranging Response received - T3 time-out;CM-MAC=a4:7a:a4:6f:2c:7d;CMTS-MAC=00:01:5c:3f:be:52;CM-QOS=1.1;CM-VER=3.0;
Oct 21 2012 21:52:54
Unicast Maintenance Ranging attempted - No response - Retries exhausted;CM-MAC=a4:7a:a4:6f:2c:7d;CMTS-MAC=00:01:5c:3f:be:52;CM-QOS=1.1;CM-VER=3.0;
Here is your "own thread". The upstream power is too high and may be intermittently fluctuating even higher out of spec.That will cause random disconnects and spontaneous re-booting of the modem. Are there any excess/unneeded coax cable splitters in the line leading to the modem that can be eliminated/re-configured ?
If there aren't any unneeded splitters that can be eliminated and if your coax wiring setup can't be reconfigured so that there is a single two way splitter connected directly off of the drop from the street/pole with one port feeding the modem and the other port feeding the rest of the house/equipment with additional splits as needed and you've checked all the wiring and fittings for integrity and tightness and refresh them by taking them apart then putting them back together again, then perhaps it's best to book a tech visit to investigate and correct.
Thanks EG, I will try and find if there are any unneeded splitters, we have a total of 3 cable hookups in our apartment so perhaps there is one that can be removed/bypassed. If I can't figure it out I will just call a tech. Thanks for the help, I really appreciate it.
I am having the same problem with the same log errors. My upstream power is also 49/50. I have had no problems for a full year and there is only the one splitter at the box. The only change in the configuration was the most recent automatic firmware upgrade. I have read elsewhere the problem has to do with DOCSIS 3, that problems with ranging cause the timeouts. The problem seems far too common to be anything other than faulty firmware. Is it possible to revert to the previous version if a new one that works correctly is not available?
When the tch arrives make sure he checks the drop for noise.... I suffered with this stuff for 3 years and several tech visits - but they never checked their line coming into the house. It's been a month now since the put in a new wire (which they still have not come out and put in the ground yet) from box to trailer and we haven't had ANY repeated resets - only two that I am aware of and those seem to match outages that others in the park had so it must have been on the system side.
Well I had the problem for a couple days. It was intermittent but would last for hours at a time. Eventually the whole area went out and Comcast had an outage notice for much of the day. When Comcast came back online the problem was resolved, and my power had dropped to 45. There was no change made on my end. I have no idea what they might have worked on. I see people griping about this with power levels above and below 50 so I don't think that is it. Something on the Comcast side is funky. Since my particular problem seems connected to a whole area outage it seems it was never my modem to begin with that was having trouble.