Is there a wired Sonos component?

Are there any changes in the player status LEDs when this happens?

Could the router have rebooted? 

Thanks Ratty. Not checked all status lights yet, only on my Sonos One SL which was flashing, will wait for next reset to occur. No obvious reboot from router that i have noticed, but presumably it could be a transient thing.

Have had system stay on when using my three so will gradually add in rooms to see if one of them triggers the reset.

Beginning to suspect the 1SL.

A flashing LED suggests a soft restart, typically triggered by a need to reconnect to the network.

A single player restarting wouldn’t make the whole system reset, though it could of course cause that player to drop from a group.

Do you have any Sonos components wired to the network? Are there are WiFi credentials stored in the system?

It’s definitely the 1SL, system has worked perfectly with it taken out of the group. May give Sonos tech help a call as cold be a controller issue; think this may have occurred after last update.

A stupid question: the power cable is fully inserted into the base of the One SL? It can be tough to press it fully home, though of course partial insertion is usually obvious as the speaker won’t sit flat on a surface.

You could always try a factory reset of just that speaker and see if it corrects the suspected misbehaviour.

All components are wireless connections. Not sure wat the last question refers to - technophobe at work.

I understand that all may have wireless network connections. I was just checking that the One SL wasn’t losing power intermittently, from a loose electrical connection.

To factory reset a product: https://support.sonos.com/s/article/1096

After reset you’d just add it back. It’s a long shot, but worth a try.

Factory reset seems to have resolved issue this time; will see how it goes.

Thanks for your help.