If this is a question, and not a statement, then I’d suggest there are network issues, most likely with your router connecting to the Arc. Although I have to admit, I have absolutely no idea what DR P4 means. 

At the least, I’d check the Sonos for updates, to ensure the controller and the speakers are running the latest versions, then perform a network refresh by powering off all Sonos devices, then rebooting the router, giving it a couple of minutes to come back up before plugging back in the Sonos devices. I’d also give the Sonos a couple of minutes to come back up and reconnect before testing. 

However, if this doesn’t help things, I would recommend that you submit a system diagnostic within 10 minutes of experiencing this problem, and call Sonos Support to discuss it. But don’t post the resulting diagnostic number here, they get sensitive about GDPR.

There may be information included in the diagnostic that will help Sonos pinpoint the issue and help you find a solution.

When you speak directly to the Support staff, they have tools at their disposal that will allow them to give you advice specific to your network and Sonos system.

Thank you for your concern and advices.

DR is the Danish National Radio broadcast service.

I have tried mist of your recommendations and my router is placed 5 m from my Arc. All of my Sonos produkts are at latest software level.

I guess that my last resort will be to contact Sonos Support with a fresh system diagnostic.

/Sommerdal