To get an IP address from the domain, the installer uses DNS and it should return the external IP of the server.
If you're using AWS or any other hosting provider, you need to specify in config.yaml:
nat: true
However if the DNS doesn't return the external IP address (for example, you have modified /etc/hosts to install Headwind MDM and Headwind Remote on the same server), the software will be successfully installed, but the mobile agent connection will fail: "ICE connection failed".
In this case, you need to specify the external IP address in config.yaml:
public_ip: "external-ip-address"