So this is new:

I come home, check my Jolla, it's on mobile network.
I check ten minutes later, still on mobile, hasn't switched to WIFI.

I select 'settings', settings shows a loading screen and then disappears again. After a few tries it finally opens.

WIFI in the settings is switched off and ->can't be turned on again<-

Mobile Network in the setting tells me it is deactivated. I can tap it and the light in front of the setting goes on, but it STILL tells me it is deactivated.

However, I DO have internet connection, FB App works normally.

I already had this problem once today, and when I turned off the Jolla, a red notification light remained and I couldn't turn it back on, had to remove battery.

Will report if the same happens now.

Edit: Reboot worked fine (maybe it just needed more time to boot again), wifi connected fine. We'll see if that is a reproducable bug.