HI
i have CCU 2 withemperatur sensor. in the ccu2 the sensor is always online, but in home assistatn the sensor is often offline, sometimes it shows values, sometimes not. what can i do? all other devices over ccu works fine.
what integration are you using in HA?
Over configuration.Yaml, Cant find Ort the Version
Sounds like you are using the official integration.
I can recommend Homematic_Local instead.
It is far more active maintained.
The HA team is actually recommending it over their own integration. 
Last, not least, work has just been started to completely rework the HomeMatic/homematicIP device integration layer within Home Assistant itself. While still in an early development phase this complete re-design will come with great new features and a way easier setup and a more complete device integration of all your HomeMatic/homematicIP devices.
Source: New Add-on for HomeMatic/homematicIP support - Action Required - Home Assistant