C7000v2 Daily Slowdown

I've read so many posts about the c7000's that didn't work properly out of the box, or that ultimately had issues with ISP service (account-wise, or physical lines) but none that I can find have my specific issue.

I've had Comcast in northern Indiana for years now, and their modem/router combos have always worked well enough, but I wanted to switch to Netgear in order to stop paying long term rental fees.  I had great service with their hardware (~700 down, ~25 up).  For awhile after I started using my Nighthawk combo I had great service and everything seemed to be running the same.  A month or so ago I noticed streaming services on the living room tv (through a heavy wall, over wifi, but never issues before) were so slow that both Netflix and Youtube were lowering my quality.  Running speedtest (as well as Fast, and a few others) showed around 15 down, 20 up.  I even got tests that showed 8 down, and 25 up with expected low ping.  Factory reset was my final option after tweaking settings for days, and it seemed to work.  A week or two later, and now I'm having to reboot my c7000v2 on a daily basis.  With no one home and very little traffic over the network, I'll come home to speedtest results in the 10-20 down range, but the issue is immediately cleared up upon reboot...for a matter of hours or a day.  Channel 4 on my connection info shows 2810 correctable/14609 uncorrectable and every channel has 3.1-4.1 dBmV.  I checked all the ports from the pole, all the way to the modem and they all clearly work because a restart will get me back up to 6-700 down.  Am I just missing a key part of the setup or maintenance, or is this combo just as sketchy as it seems?