Maybe move nearer to your main router, close the Sonos App fully (slide off screen) and then toggle off/on the mobile device WiFi network connection. Then open the Sonos App and try again and see if that perhaps resolves the matter.
 

Check security software/VPN/WiFi Calling etc; is not in use and interfering with the connection and also see if toggling off ‘Private WiFi Address’ and/or ‘Limit IP Address Tracking’ in the mobile devices WiFi connection properties helps to get the Sirius XM stations working again