I now tested to switch back to the long Port-Name. Without any effect.
Unfortunately the firmware update i tried did not work either. I used this instruction: How to update conbee II on hassio with deconz/phoscon integration? - #12 by thomas-svrts
It fails with “bootloader failed”.
Irritatingly, it doesn’t find suitable firmware as described in the instructions; I have to select it manually.
Normally i would thought there is a problem with the conbee 2 hardware, but as i put it back to the RP3 it works like a charm.
I although tried today a completely new restore of the new N95 from a fresh backup from the RP3, but this does not fix it either.