Apple TV 4g radio apps buffering

On my Apple TV 4g, radio apps (Receiver, MyTuner, etc.) play great for 5-10 minutes, then endlessly buffer. This even happens on proprietary radio apps (e.g., KEXP). System is up to date, as is Airport Firmware. No problem with any other streaming. I have deleted and reinstalled apps, selected and deselected most of the preferences, restarted the unit...nothing helps.