You have described the problem I have had for the last 10 Months exactly.
I have found that connection integrety makes a big difference. F connectors should be tight. Center conductors scraped bright, No corrosion or dirt. My signal levels ar +7 to +10 Down and +50 up. I have a 7 db splitter in the line which means the downstream level at the ground block is +17 (Way HoT).
Sometimes I can go weeks without a reset and other times it's 3 times a day. I do notice in the modem log I get a lot of CODE 16 and CODE 24's. I run a Ubiquity UDM pro which also has a modem monitor/reboot accesory. When invoked It reboots every few hours (probably when the codes 16 and 24 are going) so I shut it off. I also get client errors say slow dns or tcpip traffic.
My suspicion is that internet or dns is interrupted. Sometimes it recovers on its own. Sometimes it dosen't.
This dosen't solve your problem. I'm just telling you are not alone. My suspicion at this point is that it is a network stability issue and we are not allowed to peek behind the curtain.