Internet Dropping 3-4 times a day. Each time with the following errors: UCD invalid or channel unusable and SYNC Timing Synchronization

My internet connection will fail several times in a day. It dropped three times one Wednesday, 1/22. Then did not drop again until yesterday 1/24. It has dropped five times in the last 24 hours. In about 2 - 10 minutes the internet will be back. The modem lights appear to show a good connection during the outages. When I look at my modem's event log, I see there are Critical Events that correspond with these outages. They are always:

UCD invalid or channel unusable

SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing

Also, SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing