Ok now I have a new problem. All things are detected and online but I can’t receive or set their status.
This could be caused of the docker installation and using the docker host (synology) Network config.
As gateway access within the homematic gateway I have the CCU IP and as Callback Network Address the docker host ip (Synology NAS).
Or is there something else which could cause this?
All other items from other bidings work as expected like the Hue binding.
NoTechi
Update: Also self solved 
My items file previously created needed an update …