The device is about 20 meters away from the gateway.
At the best value it was perhaps 10 meters.
According to the instructions, I should set this here:
The instructions say that I should enter something in the JoinEUI.
The main thing is that it is in HEX and I can press Confirm.
One statement in a video was also “that the console would report if the JoinEUI is not okay”.
So I used the password manager to generate a 16-digit hex value.
The code for the T-Beam also contains the following line:
//Set FS for RX2 (SF9 = TTN,TTS EU)
LMIC.dn2Dr = DR_SF9;
In my opinion, the set frequency should fit.