I am having the same issue. Video quality is fine, audio (when on a radio station from Spectrum) is cutting out often. Very annoying. I have tried changing everything (channel, etc.).
At this point I'm fairly certain my problem is not my internet feed or my Roku Ultra. I tested the Roku direct to the TV (w/o the AV connected) for 2 days with no cut-out issues. So. A week ago I took my Yamaha AV to an authorized repair station. Still waiting for them to diagnose. Best of luck.
What is "AV" ? I have three ROKU devices in use (2 ROKU 3 and 1 ROKU Ultra). They are all on separate TVs. ALL are doing the same annoying cutting out when on a music channel.
AV is my Yamaha Audio/Video surround-sound receiver.