So, the speaker is communicating to your router, but not through your router to reach your controller, which is unusual. What device do you run your controller on? Have you ‘disconnected’ the controller from your system, then reconnected it? 

I’m sorry to hear about your power issues. I’m often in a similar state, living on an island. But usually, when the power comes back on, I don’t lose connection. I’d be awfully tempted, due to the potential power surges that occur with power interruptions and recovery, to do a full network refresh, as a precaution. Unplug all Sonos devices from power yourself, then reboot your router (probably easiest to power cycle it, too), and wait two minutes to plug back in your Sonos. This will refresh the OS on all these devices, and clear any power surge related issues that aren’t permanent, as well as assign new IP addresses to the Sonos (although I don’t think that issue is yours, as the device is already playing music). 

If either of those don’t  make a difference, I would recommend that you submit a system diagnostic and call Sonos Support to discuss it. But don’t post the resulting diagnostic number here, they get sensitive about GDPR.

There may be information included in the diagnostic that will help Sonos pinpoint the issue and help you find a solution.

When you speak directly to the Support staff, they have tools at their disposal that will allow them to give you advice specific to your network and Sonos system.

Thanks so much for your reply.

i tried uninstalling and reinstalling the controller app to no avail.

finally today I got around to turning off the the speakers and rebooting as per your instructions . And it worked.

Appreciate your help.