Does this behavior occur just for one radio station in particular or does it occur regardless of the station being played? Can you please try playing the same radio station to the Nucleus’ HDMI Output as a test and let me know if it stops as well?
You don’t need to have anything connected to the HDMI port, just enable it in Settings -> Audio and then let it run the same station in the background. Also, you mentioned your switch model but can you provide more info on the router used?