It doesn’t always happen, but sometimes when I leave home, the phone doesn’t manage to switch to mobile data. Usually going into airplane mode for a few minutes and then back resolves it, but as the universe would have it, it usually occurs when I really need to do something important right out of the door.
Has anyone had a similar issue? My APN settings are correct and I’m on Congstar in Germany (Telekom network). It seems like a bug to me since it doesn’t happen consistently.
If not done already, make the Developer options visible by tapping on the Build number in Settings - About phone a few times until you are being declared a developer.
If it is disabled, enable Settings - System - Advanced (necessary or not depending on the Android version) - Developer options - Mobile data always active.
The description of this switch is “Always keep mobile data active, even when Wi-Fi is active (for fast network switching)”.