Hi Bernd,
The interval between status messages should be 30 seconds, not 6 minutes. However this might just be a logging issue. Could you check the gateway consoles ‘Last Seen’ message for a couple of minutes? The value should not exceed 35 seconds.
Just to make sure, you are using a 868MHz model, not 443MHz?
Could you post a picture of your setup?
Best regards,
Jac