The upstream power is borderline / too high and may be intermittently fluctuating even higher out of spec. That can cause random disconnects, spontaneous re-booting of the modem, and speed and latency problems.
In a self troubleshooting effort to try to obtain better connectivity / more wiggle room, check to see if there are there any excess/unneeded coax cable splitters in the line leading to the modem that can be eliminated/re-configured. Any splitters that remain should be high quality and cable rated for 5-1002 MHz, bi-directional, and no gold colored garbage types like GE, RadioShack, RCA, Philips, Leviton, Magnavox, and Rocketfish from big box stores like Home Depot, Lowes, Target, Wal-Mart etc. Splitters should be swapped with known to be good / new ones to test
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 check for and clean off any corrosion / oxidation on the center wire and put them back together again, then perhaps it's best to book a tech visit to investigate and correct.
You are having some signal issues there, your error log confirms your disconnection issues as well. You have a few channels that didn't lock, some poor SNR on others and some error correction issues. Your power levels are okay, but your signal is not clean. Usually, this is caused by bad/substandard wiring. It's possible it is a Comcast issue, but most likely the problem exists between the tap (pole) and your modem.
See the troubleshooting guide.
Your power levels are okay,
Sorry but the upstream power is not o/k.... 54 dB on channel 3 is too high. And the rest are marginal. And see the part that I wrote about possible intermittent fluctuations even farther out of spec........ There is an Impairment of some sort....
Whatever you say. Doesn't matter to me what that one chart says. It doesn't take any possible intermittent fluctuations in to account. 54 dB is too high. There is no wiggle room. It's just common logic....
The operational range is actually 57dBmV+ and some modems are running just fine beyond that. The plant is a lot cleaner than it was in the past and thus the tolerance for signal variation has greatly increased. So 54dBmV is fine and there is plenty of "wiggle room".
Sorry OP if we hijacked your thread!