Does the playback volume seem to be okay when playing audio separately to the Era 300 speakers? Have you another couple of speakers available that you can ‘bond’ as surrounds to the Arc instead, to see if they work okay?

I’d reproduce the issue, then submit a system diagnostic , and call Sonos Support to discuss it.

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 phone folks, they have tools at their disposal that will allow them to give you advice specific to your Sonos system and network.

Thank you Ken and Airgetian. I called Sonos support and was pleased I hardly had to wait. The service agent walked me through a diagnosis and showed my how to solve my speaker disorientation issue.