Your report suggests an issue with your Sonos system reaching the Pandora servers. This could indicate an issue with your speakers reaching your router, your router reaching Pandora’s servers, or even Pandora being temporarily down, it’s hard to tell, and we in the public don’t have access to the same hard data that a Sonos rep does, although I’m not yet overwhelmed with their Chatbot.
What I’d suggest is a simple network refresh, which will adjust a plethora of potential issues, without breaking anything. Unplug all your Sonos devices from power, then reboot your router. Give the router a few minutes (at least two) to come back up, then plug back in your Sonos devices. Give them a couple of minutes to reboot and reconnect, then double check for any updates from Sonos in the controller, which will cover both the firmware on the speakers and the software of your controller. Once any found have been applied, do your testing.
I think, depending on what you were experiencing, this should remedy the issue.