It could be IP address issues, instead of wifi interference , which would impact either wired or WiFi connected devices.
Try unplugging all Sonos from power, then rebooting your Orbi. Wait two minutes, then plug back in your Sonos devices, and wait for them to boot before testing.
If this doesn’t work, 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.
For what it’s worth, when set up as surrounds, they aren’t connecting (directly) to your Orbi, but instead to the Sonos soundbar, across a (hidden) 5Ghz network. They do receive proxy IP addresses through the Arc’s connection, though.
Not all WiFi interference comes from other WiFi devices, I had a problem device that didn’t even have a radio in it.
After much help here I was reduced to simply unplugging everything. My Sonos worked. Plugged a few unlikely devices back in, still worked, did more, still worked, did more and it acted up again. One at a time I unplugged the last batch until I found my WD external hard drive was spewing RF and disrupting the Sonos connection. Again, no radio in it!
