Upstream issues and modem errors.

The upstream power is way too high / out of spec. That can cause random disconnects, spontaneous re-booting of the modem, speed, packet loss, latency problems, and the un-bonding of channels.

In an effort to try to obtain better connectivity / more wiggle room, check to see if there are 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 from Home Depot, Target, Wal-Mart, etc. Splitters should be swapped with known to be good / new ones to test.

Also check the coax cable for any damage such as cuts, nicks, abrasions, kinks, sharp bends, etc.

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.

Good luck with it !

Quite welcome ! It could be local to you or farther up the line somewhere. If the upstream power is still that high then that needs to be addressed. Have you tried any of those tips ?

Yes. If there is nothing more that can be done to improve the connection quality, then you'll need a tech visit as stated. 

Bear in mind that if the premises facing techs can not find or fix a problem at your home, it is they who are responsible for escalating it up to their line / network / maintenance dept. techs. The problem may lie beyond your home in the local neighborhood infrastructure somewhere but it is their S.O.P. to start at the home. And if the problem is found to be on their side of the demarcation point, there will not be any charge.

Good luck ! Please post back here with how things turn out.

Just as a quick update to this, I work nights and all my testing and troubleshooting has been done during the night and early morning. Something I realized was that during the day (around 11am) the upstream is completely fine. Is there a representative from xfinity that can confirm whether this some kind of work or maintenance going on during the night that would cause this? I'm still scheduling a tech visit to check all the lines, but clearly something is happening at night that is causing upstream issues that isn't happening during the day time.