IP address conflicts.  Specifically the IP on the iPad.  Reboot router.  Then reboot each Sonos device.  Then reboot the iPad and any other controller.  You can prevent this in the future by reserving IP addresses in you router for each Sonos device.

Thanks. - I have tried this and it isn’t a solution, as I’ve now had the issue with other controllers. It appears that the issue is whether my Move is on- or off-line.  I’ve tried resetting it to factory settings and that hadn’t resolved it -I’ll try reserving a specific address for it and report back.

you may need to disclose more information about your network settings - are you using a meshed wifi network? do place the move in different rooms? are your other Sonos devices wired or is at least one of them wire connected to the router?

Yes, it’s a mesh network -- and, yes, the Move certainly gets shifted from one node to another.   All the other devices are in fixed locations, and often moving the Move, shows it as the priority or only node in the Sonos system -- of course, in that respect I’m also moving the controller(s) to different nodes.

Time to look more closely at the node connections!

Thanks

while the Move does not use SonosNet, do you have any of your other Sonos devices wire connected to your router?

By default most WiFi meshes contain a router, in the primary node. If the WiFi remains active on the main router, or there’s anything other than the mesh primary wired to it, the network would be split with clients on different subnets. Sonos controllers/players on one subnet couldn’t see Sonos on the other.

Either put everything on the WiFi mesh (wireless or wired), disabling the router WiFi, or switch the mesh into ‘bridge’ mode.

Thanks, but that’s the way my system is set up - router WiFi is disabled.

Is anything else plugged into the router, apart from the primary node of the WiFi mesh?

No, all the system is driven from the mother node of the mesh - ethernet connection to the router

And what is the make/model of mesh?

How does the Sonos system connect? Are any Sonos devices wired? WiFi, and which band? (The Move obviously needs WiFi.)