Hi Mihai,
thanks but this doesn’t help. We are talking about 433 MHz settings, not 868 or so. The App has an internal limit on this frequency. If you set the power to 20 dBm and press save, then the power is 12 dBm again after the reboot, so there must be an internal limit. Also with the CLI, i tried it a few times.
As garth pointed out, the source code must be changed. It might be a bit disappointing for others who have the same problem and lack of time and skills.
I will however take the time and will fight to solve that issue!!! Will publish the result here then.
BTW using the HAM option runs without encryption, so it is not interesting for me (although i am a HAM indeed).