So I merged the two bridges, reset the device.
When first connecting to ETS5, the openhab log say (6 times)
establishing connection failed, error response from control endpoint /192.168.131.2:3671: could not accept new connection (maximum reached)
After disconnecting ETS5, Openhab connects just fine. But now I cannot connect from ETS anymore.
I really don’t have a clue where those connections come from!