If you can find a BOOST, it should work, it was the replacement for the BRIDGE. But both devices have been ‘retired’, although still supported in software. You’re probably better off hanging your Sonos system directly off your WiFi. See the wireless and wired systems FAQ, along with the associated FAQs. 

You should be able to find a power supply of unknown quality in various places, if you so choose. I’ve never used one, I can’t recommend one to you. 

Just to be uber clear, by ‘retired’, I mean no longer manufactured or sold by Sonos. I would guess you might be able to buy ‘new’ stock somewhere, it should work just fine. Or ‘used’ equipment should, as well, both devices are still software supported, just not manufactured. The BOOST was retired around May of 2024, according to a quick google search. All new devices sold by Sonos don’t connect to the SonosNet signal created by the BRIDGE/BOOST, but instead directly to your WiFi signal. 

I[‘d try switching to WiFi as my first option.

Amazon and others have replacement power supplies claiming to support the Sonos Bridge.

https://www.amazon.com/s?k=sonos+bridge+power&crid=3VS0RLYU36JVO&sprefix=sonos+bridge+power%2Caps%2C154&ref=nb_sb_noss_2

A used Boost is close in price and will usually work better than the Bridge

https://www.ebay.com/sch/i.html?_nkw=sonos+boost&_sacat=0&_from=R40&_sop=15

​@bob_101 

What speaker(s) do you own that are “directly” in the wall? Even if you have in-wall Sonos Architectural speakers or 3rd party speakers they have to be powered by a Connect:Amp or the newer Sonos Amp. Both amps have ethernet ports that can be wired back to your router. You can create the SonosNet in that manner which is the same as using a Bridge or Boost. My apologies if I’m mis-understanding your post.

You also mentioned that you have an older system. To me an older system consists of:

• Play:1
• Play:3
• Play:5 (Gen1 or Gen2)
• Playbar
• Playbase
• Sonos One (Gen1 or Gen2)

Are any of the above speakers the ones you are referring to?

Thanks AjTrek1. 
It is an old system installed in 2009 with multiple zone players (ZP120) with Klipsch speakers hardwired into the players

​@bob_101 

Thanks for the update. That said are you not able to run and Ethernet cable from one of the ZP120’s back to your router to create the SonosNet?

If you are you’ll want to power down all Sonos. Remove the Bridge. Reboot your router. Delete the Sonos app Connect a ZP120 via Ethernet to your router then power it up. Wait 5 minutes then power up your remaining ZP 120’s 1x1. Wait until all ZP 120’s are up. Reinstall the Sonos app and select “connect to existing system. Accept all prompts then sign-in with your credentials

Well I followed the above but the app would not pick up my system. I then went back and used another power cord for the original dead Bridge and it sparked up and everything seems to be back working! Will plod onward with this old system until it (or I) keel over. Thanks for the help!!

I’d still follow the instructions to remove the BRIDGE, it’s past it’s life. 

OOh, thank you. I don’t fully understand some of your comments, but you’ve just helped me get a first generation back up and running. It looks like our bridge just died, so nothing working. PSU to the bridge is showing 5.2Volts. Bridge now rattles, and the lights on the back are not now lighting up. So, plugging one of the speakers directly into the router with an old ethernet cable from the attic, magically lights up the system and gets the sound going again. I.e. i’ve just recreated the meshnet using a speaker instead of the bridge (i think). Which i think is what AJTrek1 and Airgetlam are talking about above. I’ve not looked at the Wifi Wired FAQ’s, as i wasn’t expecting to understand it, but it feels like this is what i’ve “accidentally” succeeded in doing… Many thanks. Fingers crossed, i have sorted out a solution, now to look for a secondhand Play 3 to replace the one i’m using as a “bridge”… 

Just remember, Sonos no longer ‘requires’ a BRIDGE/BOOST/wired speaker type device. The system is just as happy working off your WiFi signal, if you’re willing. 
 

There’s a lot of good information in the Sonos Network Requirements FAQ, the wireless and wired systems FAQ, and the wired and wireless modes FAQ.