I don’t think I’d recommend a restart of the entire system, unless that’s a last choice option. I suspect there is something else that can be fixed to alleviate the situation.
The first thing I’d do is check to ensure the radio/wifi has not been turned off on the Arc. It uses its own connection to both the surrounds and Sub, and even if your Arc is connected with an Ethernet cable, it should be ‘on’.
Maintaining a connection could also be a sign of network issues. I’d suggest a network refresh, by first unplugging all Sonos devices from power, then rebooting your router. Give it a couple of minutes to come back up before plugging back in your Sonos devices. Also, make sure you have at least 3 feet (1 meter) between your Arc and your router.
Just to be safe, I’d also check to ensure that the TV was up to date with the latest firmware, as well as the Sonos.
Finally, if none of this helps, 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
