The BRIDGE is obsolete and old enough to have developed hardware issues. BRIDGE was developed when home WiFi was not capable enough to support a wireless SONOS system. Current home WiFi can easily support SONOS. In most cases you can enter WiFi credentials into the SONOS system, then remove  BRIDGE.

If you are into self service, a typical BRIDGE issue is a failed power supply. If you can measure Voltage, the power supply should measure slightly over 5Volts. Less than this you will experience a variety of issues. If you really want to continue with the SONOS wireless (SonosNet), I suggest replacing BRIDGE with BOOST. While both units are obsolete, BOOST is more capable than BRIDGE.

Neither the BRIDGE nor the BOOST are sold by Sonos anymore, as home routers are now much more capable than before.