The Teensy LC also works.

So the problem is the Arduino Pro mini.

Hi,

Thank you.
Now it works.

The trick is D100 must be on pin 2.

I try to make the pin assignments the same for all nodes (STM32, Arduino Pro, Teensy LC Tennsy 3.1 / 3.6, ESP8266).

D100 I had put on pin 6 and
#define MY_RFM95_IRQ_PIN 6
In the sketch.

That was the mistake with the Arduino.
On all other platforms it works.
 
Many Thanks. I had already given up.