Thank you for this info. So let me repeat if I understand right.
I need to set on router for an incoming port for my host, for port 8000 to port 8000 on my local server ip 192.168.0.40 and for incoming port for my host, for port 6556 to port 6556 on my local server ip 192.168.0.40.
If I have second host for example 192.168.0.50 I need to setup for that host in checkmk server for port 8000 differend port like 8001 (image you post) and set that on my router to forward port 8001 to my local host ip 192.168.0.50. on port 8000.
I have only one host behind router for now.