Do you have any speakers or the Amp hardwired to your network/router? I have found an ethernet connection has worked well fro me for years.
If that does not help, calling Sonos support and submitting a diagnostics may help get to the root cause of your issue.
Are all the Sonos Amps located together?
If they are you could wire all of them to Ethernet and then turn off the internal radio in all but one of them. (toggle disable WiFi)
They’re all hardwired to each other and one is plugged into my switch.
If that’s the case, and the issue is indeed wifi interference, then the suggestion made by @Stanley_4 is a good one. If, however, it’s a network issue with duplicate IP addresses, it won’t make any difference, since IP addresses are used by both wired and wireless devices.
Try either assigning them reserved IP addresses in your router, or perform a network update by unplugging all Sonos devices, and rebooting your router. Wait for the router to recover before plugging back in your Sonos devices.
I’ve disabled WiFi on all the amps to avoid the interference. I will check my IP assignments on the admin tool and test. Will report back on what I see.
