Roon "Lost control of audio device"?

When Roon refers to "Audio Device" that's the Roon endpoint streamer/renderer, When you select an "audio device" in the lower right corner, it's where Roon is going, not the source of the music (i.e. a streaming service or a NAS with locally stored files if you have any). 

So that makes me suspect it's an issue downstream between your Core and your endpoint. I would look for diagnostics in the endpoint's software look for error logs, etc. and contact their support team. or post any such findings in a Roon Support ticket. Cheers,

Spencer

@ricred1 Do you also use any streaming service such as Qobuz or Tidal? If so, do you get no errors then? If not, how about a Qobuz free trial and report back if the error is on both local file playback and streaming service or not. 

If you know the error is isolated to local playback, I agree @vonhelmholtz suggestion to try a "dumb" switch vs. smart may eliminate it. I used to a Pro series Netgear that caused some weird errors. I also replaced it with a $20 TP-Link recommended by Andrew at Small Green Computer and the issue was resolved. Cheers,

Spencer

Some smart switches are like a drunken traffic cop outside a stadium after the game. They think they know how to handle it.