I am having the same issue after the update. I’m on an XA2 as well, no modifications. When I updated it, the update progress was stuck at 100% for half an hour, and the power button was not enough to restart it, I had to use Volume up + power.
Then it booted and migrated apps, but now the internet connectivity is as you describe: sporadic in that some apps work (e.g. Messenger) and some don’t (e.g. Aurora Store, banking apps). Some might work partially (F-Droid shows something at first, but then it says no internet).
This is actually not limited to Android apps! If I go to the Sailfish OS Updates settings page, it also says that it cannot check for updates because it’s not connected to the internet. If I tap on the bubble, it gives the connect interface, which however shows that it’s connected just fine!
Restarting the internet using Sailfish utilities does not help.
Are there any suggestions as to what can be done now? Should I reflash the whole OS or so?
