Unpair the Ones as a stereo pair in the Sonos app and unplug both of them from power for a couple of minutes and reboot your router. After you plug your speakers back in and you see them in the Sonos app, pair them again as a stereo pair.

Some systems have issues at update time or after power failures. Nobody has pinned down exactly what is going wrong or found a fix. What has been found is a way to avoid having the issue happen.

If you want to try this trick go to your router’s DHCP page and assign each Sonos a static/reserved IP address. Power down all Sonos devices, reboot the router and controller. Power up your Five. Power up the remaining ones once it has booted.

You won’t notice any difference from this except the odd issues at update / reboot quit happening.

Thank you GuitarSuperstar and Stanley_4.

I followed the process of unplugging the speakers (ones) - I actually swapped the speakers around, rebooted the network etc and it’s all working with strength again like before. 
I will have a look at your suggestions Stanley_4 also. I am curious though as prior to asking the question I had rebooted the network and a few other things but not the speakers. Because I am new to Sonos I keep forgetting that these speakers are running smarts and processing information etc. Could this issue have been solved by the simple process of the speakers rebooting?

The software seems a little clumsy today (sluggish and taking a while to bring up my saved albums, playlists etc… Maybe just my imagination or could that be the update?

Thabks again, R

Good that you’re back up and running. 

There is a possibility that duplicate ip addresses are being allocated when you reboot just the speakers. Rebooting the router first, and then the speakers, prevents this. This is why allocated ip addresses seems to help. 
 

You can also set Settings/System/System Updates so it doesn’t auto-update - but remember to change that option in your phone app too. Then you can select when it suits you to update. 

This post explains this issue: https://en.community.sonos.com/troubleshooting-228999/tips-tricks-resolving-random-issues-impacting-sonos-devices-6845346

For me it is a process, not a simple reboot.

All Sonos devices have to be powered down.

Router must be rebooted.

Controller must be rebooted.

One Sonos must be powered up. If you are running wired you need to start with one of the wired ones, otherwise start with any main (not sub or surround) speaker.

Then do the rest, I wait a minute between each.

Skipping any step gets odd results and/or doesn’t cure the glitch.