Looks like the writing is on the wall for Apple Server.
Dumping many services, and suggesting replacements.
As always, here is a cut and paste of some of the details in case it goes away.
Prepare for changes to macOS Server Learn about changes coming to macOS Server in spring 2018 macOS Server is changing to focus more on management of computers, devices, and storage on your network. As a result, some changes are coming in how Server works. A number of services will be deprecated, and will be hidden on new installations of an update to macOS Server coming in spring 2018. If you've already configured one of these services, you'll still be able to use it in the spring 2018 macOS Server update. These deprecated services will be removed in a future release of macOS Server, so those depending on them should consider alternatives, including hosted services. Deprecated services are listed below. Links to potential replacements are provided underneath each deprecated service. Calendar Calendar and Contacts Server DavMail Radicale Contacts Calendar and Contacts Server DavMail Citadel DHCP Kea Dnsmasq FreeRADIUS DNS BIND Unbound KnotDNS Mail KerioConnect dovecot/Postfix Courier Messages ejabberd Openfire Prosody NetInstall NetSUS BSDPy VPN OpenVPN SoftEther VPN Tcpcrypt Websites Apache HTTP Server Nginx Lighttpd Wiki MediaWiki PmWiki XWiki