Hi @Jimmyrjames,

Welcome to the Sonos community. Thank you for reaching out to us and for your detailed post describing your concern.  We appreciate your effort in resolving the issue. To help you out why one of your Sonos speakers is sometimes not working, I'll be requesting from you in submitting a diagnostic report and include the confirmation number in your response to find out the cause. Please let us know if you have any further questions or concerns, we'll be glad to assist you. 

Hi Rowena B,

thank you for your help. I’ve submitted the report confirmation number 967939920.

Since writing my earlier post, I now seem to have only the play one that was missing earlier and none of the other speakers that were previously present (beam and two other play one’s). I don’t know when this ‘switch’ happened so the diagnostics may be of the current situation and not the earlier one. 
thank you 

After resetting the sonos app it is now back to its original state that I originally wrote about (with three speakers connected (beam, and two play ones) and missing one play one labelled dining room. I therefore have resubmitted diagnostics with confirmation code 1126038599  

Thanks

Many have found setting a static/reserved IP address for each Sonos helps power loss and at update time. Use your router’s DHCP page, power down Sonos, reboot router and power the Sonos back up.

Thanks Stanley, unfortunately my ISP doesn’t support static IP addresses so I’m a bit stuck. I’ve done a factory reset on the problem speaker, rebooted the router and re added it to the system which took 3 attempts due to it not adding. Seems to work now, but just strange it’s only the one speaker that is problematic. 

Rather than using ‘static’ IP addresses, look in to how your router allows reserved IP addresses in the DHCP table. Many ISPs don’t allow static addresses, or charge extra for that, but I’m not aware of any that block you from setting up reserved IP addresses in your router for your local LAN. 

Thanks Bruce,

have just logged into the router and have reserved all the IP addresses for my 4 Sonos products, rebooted the router, turned off and restarted all Sonos speakers but appears back to square one. On the plus side they all now appear to have the same IP address as they did earlier (obviously different from each other but same as they had before router reboot), but now only have one speaker in my system (it’s always the same one). 

Hmmm. Well, reserved IP addresses is a step forward, certainly. I’d recommend a second diagnostic, since you pave changed the network (although not visibly, apparently) and wait to see what Sonos says. 

I have just tried (not for any particular reason) assigning each Sonos a sequential IP address 192.168.1.11, 12, 13, 14 rebooted router and speakers and now it seems to work and it found all of the speakers on the network. Before, the one speaker it either found (or the only one it couldn’t find) had an IP address starting with a zero (192.168.1.09), and now it starts with a 1 (192.168.1.14). It might be pure coincidence as I have no idea why this would work, but seems to have fixed it after one reboot at least. I’m a bit too nervous/can’t be bothered to test out with another router reboot just to test the theory, but it works now at least! 

Thanks for your help with getting the static IPs up and running Bruce, would have never known that without your help.