It gets worse. I stupidly uninstalled the app and reinstalled it from Google Play. Now I can’t ‘Join an existing system’ - the app locks up clicking that button too.

I’d try a couple of things. First, I’d wire one of my Sonos devices to my router with an Ethernet cable. I’d try the controller then, and see if that makes any difference. Next, I’d try a full network refresh, by unplugging all Sonos devices from power, then rebooting my router. I’d wait a couple of minutes before plugging back in the Sonos devices. Next, if that doesn’t help, I’d delete and re download the controller, making sure to ‘Connect to existing system’. Finally, if none of that helps, I’d 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.

Ah, I see you skipped further in the process. I’d try the cabling first, then I’d make the call to support. 

Thanks for the advice. After finally getting back into the system I don’t think it is my network, or the speakers. I can control the speakers which are currently in the system, but as soon as I try to do anything in the Settings menu the app locks up.

That sure sounds like network interference of some type, between your speakers and the router. The network refresh would be a good idea, as would a subsequent call to Sonos Support. 

I’m 99% certain it’s the app. 

I rebooted the router, and all configured speakers are getting the correct IPs. I can control the beam, sub-mini with two rears (for music and TV), and also two individual Sonos speakers are working but the app still locks up whenever I try adding a speaker or creating a sterero pair.

I’m leaving it for today and will wipe everything Sonos-wise tomorrow and start again

Important to note that the controller device needs to be on the same VLAN as the Sonos speakers. Sonos software doesn’t communicate across VLANs or subnets. 

I was 99% certain it wasn’t the VLAN because it was completely open, and I hadn’t got round to creating any firewall rules to lock it down but to be sure I restored my router from a recent backup pre-VLANs.

With the speakers back on the same network as everything else the app still locks up whenever I try to change the wireless network, join an existing system or add a speaker.

I wired a speaker using an rj45 and I can see it gets an IP but I still can’t connect to a system or add a speaker.

I spoke to Sonos support and after uninstalling, reinstalling, rebooting etc the answer from them is to wait for Sonos to resolve the problem but there’s no ETA on when that will be.

I’m left with a set of speakers and no way of any of them :(