First, remove the BRIDGE from your system, and hang your Sonos from your WiFi or wire an Ethernet cable to a speaker. The BRIDGE is fairly well known to fail on the power supply, and makes tracking connectivity issues extremely hard. Many, many years ago, Sonos replaced it with the BOOST, but even that has been retired now. 

Restarting your phone won’t likely do much, as you’ve found out, the app is only a ‘window’ as to what is happening on the speakers. I would likely first try a simple network refresh, by unplugging all Sonos devices from power, then rebooting your router. Wait a couple of minutes, then plug back in your Sonos devices. Give them a couple of minutes to boot back up, too, before testing.

If this doesn’t work, 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.