By default, unless your macOS server is configured to work with a domain name, macOS will append the suffix .local to its chosen hostname. The configuration tools for Harmony will include this suffix when registering the machine's hostname in its configuration.
This can cause a problem when working in a mixed platform environment, as only machines running on macOS can communicate with your machine using the hostname with the .local suffix. Machines running Windows or GNU/Linux will only be able to communicate with your macOS machine using its chosen hostname, without the .local suffix.
To remedy this, you can manually override the machine's hostname and remove its suffix. This way, the configuration tools for Harmony and the machines trying to communicate with your macOS machine will use the hostname without a suffix.
NOTE You should only follow this procedure if you do not intend to configure the machines in your network to work with a domain name, as macOS will not append the suffix .local to the hostname of computers connected through a domain.
In a terminal, obtain your current machine's hostname, as understood by macOS, with the following command:
$ scutil --get HostName
If the result is the hostname you chose for your machine followed by the suffix .local, override this by typing the following command, where <hostname> is the hostname you chose for your machine, without the suffix .local: