My thoughts are it’s some kind of device-discovery issue across the network - it might perhaps be something on your mobile device blocking its discovery, or the multicast discovery packets are having issues communicating across your network/router. What router and mobile device are you using?

Note when the Move is on its charger-loop, the speaker is merely in ‘standby’ rather than ‘sleep’ mode so you should always see the speaker when it’s on its charger. My Move never fails to show here.

I have a Ubiquiti Dream Router.  Default config.  Both my phone and the Move are on 2.4ghz wifi channel, same SSID.

FWIW - My WiFi is a plume WiFi AX mesh system (UPnP enabled). All Sonos IP addresses are reserved in the routers DHCP reservation table.

 I am using iOS Sonos controllers (iPad/iPhone) - On those controller devices I have no security software enabled like VPN, Firewall etc. I have disabled WiFi calling, switched off mobile data access by Sonos App. I have also disabled ‘Private WiFi Address’ (MAC spoofing) in its WiFi connection properties.

So maybe try some of those things, as perhaps that might help you with device discovery across the LAN subnet.

I don’t know your chosen router (sorry), but maybe see if this link, that I stumbled upon, might give you some things to perhaps try… 

https://github.com/IngmarStein/unifi-sonos-doc

Thanks Ken.  I will continue experimenting.  But it shouldnt be this hard!  Sigh.

I agree. It’s not something I have seen widely reported though here in the user community, so my thoughts are it’s a local network/controller discovery issue (something to do with your local setup) and I’ve just simply listed all I can think of (off the top of my head) to try to assist you to perhaps sort it, rather than just letting it reoccur. Honestly I’m not seeing the issue here, so it likely is something closer to Home.

I think I have solved it. But I am not happy with Sonos for the issue.  Switching from the newer standard Rapid Spanning Tree Protocol (RTSP) to the older Spanning Tree Protocol (STP) seems to have fixed the problem.  Discovery of the Move is now immediate.  And that would also explain why my older, cheaper router would not have had a problem ... it likely also defaulted to STP.

At some point Sonos will switch to newer system internals and the Linux they are using should then support RSTP and a lot of other newer protocols. No idea when but I do know it will be a huge and expensive change.

Ah glad to hear the Unifi & Sonos document link helped you to sort it.

Yes it did Ken.  Thamk you for pointing me in the right direction!

What you describe matches my experience... but still getting mucked up status in app. Says asleep when clearly not. Did the reset you suggested...now says powered off, when clearly not. I can even get it to play using voice control ... whilst app still says unit is powered off!!! Some funky stuff going on Sonos ..

 Hope there's a fix out there soon!

I would try a reboot of the local router and mobile controller device. Also power off the speaker off it’s charger by holding the rear power button for 5+ seconds until you hear the descending shutdown tones, wait 10+ seconds and return the Move to its charger loop and see if that fixes the issue. If not then try a Sonos App reset as mentioned in this link:

https://support.sonos.com/en-us/article/reset-the-sonos-app

Then follow the instructions to connect the App to your existing Sonos system.

Hope those suggested steps helps you to fix the issue.