BRIDGE is at end of life and can cause intermittent, hard to describe system issues. While replacing the BRIDGE power supply may resurrect it for a while, we suggest that BRIDGE be removed form the system. You can wire another unit to the network or convert to WiFi. When BRIDGE was introduced, WiFi SONOS operation was not possible. Now, with much better WiFi hardware, most home networks can support SONOS over WiFi.

My initial guess is your system likely switched to using the local WiFi, but your initial post is lacking in detail on whether the devices were connected to the router and whether you fully closed the App etc.

Maybe try removing the WiFi credentials from the Sonos app and rebooting all, so they revert to using SonosNet only… if the Bridge still does not work, it might have the ‘usual/known’ issue of voltage fluctuation due to its age, or a faulty network cable, in which case you can always just wire another Sonos product from your system in its place to act as root-bridge.

Worst case grab a (recently discontinued) used Boost to replace your Bridge.

I’d spend the money on a refurbished One SL rather than a Boost myself. It will work better and you get an additional speaker in the deal.