Daily disconnects, hours long

For the past three days, every day like clockwork, my modem is unable to connect to the internet from 11:30ish to 4:00ish. My modem is a MB8600 and until the last few days has worked great with only minor, intermittent issues that are usually solved with a power cycle.

However, these issues aren't resolved with a power cycle. The outage map reports no outage in my area, but the next zipcode over (which is only a few blocks away) has reported an outage of 1-50 people affected each time. In fact, it still shows that outage is happening right now, even though my internet is unaffected.

Cable TV works fine, and I don't use Voice. When my modem can connect and sync (arrows and globe blue) everything works fine for the rest of the day, into the next. But as soon as it becomes lunch time, it seems like the hamster falls off the wheel.

Any suggestions to remedy, or places I should start looking for issues?