If you’ve restarted the speakers, you may want to restart the router too. And check for any port blocking software, such as VPNs, work profiles, or even virus protection software.
Finally, if none of that makes a difference, I would call Sonos Support directly to discuss it.
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 network and Sonos system.