Hello hailsagan

                           First, the SNR should be above 33 on all of them.

                           The downstream power should always be between -15 and +15.

                           The closer to 0 the better connection. Finally,

                           your upstream power should always be between +45 and +51

                           On all of those values you should not have more than 3 decibels (or dB) between the lowest and the highest

                           By having the values in less than that, your device will have interrupted connection, slow or no connection at all.

              Since the values are in accepted level we would suggest you to take a tech appointment from your Internet service provider to check the cables outside your home and also check the lines using test modem and monitor connection for next 24hrs to isolate the issue.

Your cable connection page has errors on it (indicating an issue with the line) and the log is showing issues connecting back to the cmts. You’ll have to check with the ISP if they were doing work in your area. 

Thanks all for your assistance. I had a tech out yesterday and they found some issues, apparently “the messenger line was ripped off” but when I asked further questions the tech was pretty cagey.

Things were going well all day after that, but it looks like it dropped out again around 1:13 AM: These are the logs that caught it going down (including the strange 1/1/1970 reading).

The red line indicates post repair (though the No Unicast error at 14:18 was right after the repair but there was no outage).

I also have the most current upstream/downstream logs:

 

Considering the recent issues are time related (and that weird 1970 one) some steps I have since taken include:

• Unchecking “Automatically adjust for Daylight Savings Time” in the system settings of the router
• Changed the 3 time servers to be pool.ntp.org servers

Will update if any further outages occur, hoping this post repair logged incident was a fluke!

Thank you for the details, here the upstream values are not in accepted level so this needs to be checked again after reconfiguring the modem 
so please do hard reset on the modem then check again the signal levels.
For upstream channel the accepted range for power level is +45 to +51 dbmv.