When playing, the surrounds will communicate directly with your Playbar over a 5Ghz Ad-hoc wireless connection, so ensure the WiFi is ‘ON’ on each of the players… see this LINK and check that there isn’t anything in between/nearby that may interfere with the wireless connection (other Wifi products, Bluetooth device, vase of water/flowers or baby monitor etc.)
If issues persist, then I would chat/contact Sonos Support Staff via this LINK with your diagnostic report reference to see if there might be a hardware issue.
Update:
The problem was not that the devices was not on WiFi. All devices could be reached on my mesh device.
I had connection to all devices and WiFi was enabled.
After a support session with Sonos we located the issue after analyzing diagnostics and setup.
My setup is (simplified): Router → Mesh → WiFi / LAN → Managed Switch
At some point one of my Play:1 was wired to a managed swich and accourding to Sonos support the devices are not “happy” with that setup.
I needed to connect a device as close as possible to the router (wired setup) to create a stable SonosNet.
Therefore I connected my Playbar direcly to the router and all other devices connected to SonosNet and surround speakers worked again.
Best Regards Martin