How can I adjust my Android device so that the VPN connection is always on?

Since the connection management using an Android system is not defined by the settings of a specific application, you can only define this directly in the device settings.
Proceed as follows:

1

Open the Android settings and search for VPN (alternatively, the setting should be under Connections > Additional connection settings > VPN).

2

Tap the cogwheel next to the G DATA VPN entry.

3

Activate the option "Always switch on VPN" and then "Block connections without VPN".

If you use these options, your device will not be able to connect to the internet unless it is connected to a VPN server!