Thanks @Larx,
that’s what I did, unfortunately it doesn’t work.
From the homegear log, when the link starts there is a data transmission, then everything stops 
04/12/20 15:15:46.491 Info: Client with IP ::ffff:192.168.1.100 is calling “init”.
04/12/20 15:15:46.491 Info: Adding server “
http://192.168.1.100”.
04/12/20 15:15:46.491 Info: Calling init methods on server “
http://192.168.1.100”.
04/12/20 15:15:46.996 Debug: Adding method system.multicall
04/12/20 15:15:46.996 Debug: Adding method event
04/12/20 15:15:46.996 Debug: Adding method newDevices
04/12/20 15:15:46.996 Debug: Adding method deleteDevices
04/12/20 15:15:46.996 Debug: Adding method replaceDevice
04/12/20 15:15:46.997 Debug: Adding method listDevices
04/12/20 15:15:46.997 Debug: Adding method system.listMethods
stop 
The homegear administration ui works fine and I can see the devices in both homegear and homeassistant …