hi @Smithcj I have had no issues at all with macOS Big Sur, neither with macOS Monterey - check you Sonos App version (currently version 13.4.1) on your Mac and speakers
Try unplugging your Sonos speakers from power for a couple of minutes and reboot your router and Mac. You might also remove Pandora in the Sonos app and re-add it.
I agree with @el rubio , inasmuch as it sounds more like a network issue than with the app running on either Big Sur or Monterey. What source is running your music? If you’re streaming from the internet, then the computer isn’t even in the equation, it’s only there if you’re playing music stored on the Mac’s hard drive.
@GuitarSuperstar’s suggestion would clean up any potential duplicate IP addresses, which certainly could cause the issue you’re describing.
Thanks for your input!
I’ve been reading about WiFi interference. I just added a WiFi thermostat and the box sits next to the router, which sits next to the Sonos box. I think I’ll unplug the WiFi thermostat for a day and see what happens!