deConz, raspberry pi, Rest api

Dear all,

I am desperately trying to access the REST API for a Xiaomi vibration sensor (in order to increase the sensitivity).
I am running the deConz (version 07:44:02:957 GW firmware version: 0x264a0700) on the last version of HASSIO (3.12) on a Raspberry Pi 4. All is working very well with the existing integration and i see every sensor in the Hassio.
Now, even though i add the port 40850 in the Network settings of the deConz setup, i am unable to access the REST API from an outside computer.

Is there any instruction “for dummies” on how to do it?

Many thanks,