I’d first try a simple reboot of the Arc and Sub. To be honest, while they’re both unplugged, and for safety’s sake, I’d reboot the router as well, and wait to plug back in the Sonos until the router has come back up. 

Check to make sure the Arc isn’t muted for the Bluetooth connection, too. It’s a mistake I’ve made more than once The volume control is on the sending end, but mute still works on the Arc. If you have your LEDs turned on, you should be able to tell, I don’t, and rarely notice their status, but when a device is muted in Sonos, the LED always works…you just have to notice it. 

Note that Bluetooth only accepts one connection, so if it’s connected to your laptop, it will reject the connection from your Android. In order to switch back and forth, you’ll need to turn off the Bluetooth on one device in order to connect to the other…or at least, that’s the way Bluetooth is supposed to work. 

If the above doesn’t help, I would recommend that you submit a system diagnostic within 10 minutes of experiencing this problem, 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.

Dear Brian,

thanks a lot for such a valuable input.
Turning off all and unplug from electricity overnight resolved issue in brilliant way. All turned on again in the morning and everything seems to work properly. The hard reset is a miracle solution :-)

Thanks and kind regards.
H.