Open Directory has never been this easy to setup for a basic environment as it is in macOS Server 5.4 (for macOS 10.13 running on High Sierra). As with almost any previous version of macOS Server and Open Directory, once you’ve installed the Server app, run the changeip command along with the -checkhostname option to verify that the IP, DNS and hostname match. If (and only if as it will fail if you try anyway) you get an indication of “Success.” I know, I know, you’ve been told that you didn’t have to do this kind of command line stuff any more… But really, you should – and if you don’t…