A support document published by Apple sheds light on what services macOS Server is leaving behind soon, and provides possible options for those needing replacements.
The support document, dated Jan. 24, 2018, was released one day after the latest macOS Server beta. In the notification, Apple says:
BlockquotemacOS 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.
Features listed as being purged from basic installs of macOS Server soon are Calendar, Contacts, DHCP, DNS, Mail, Messages, NetInstall, VPN, Websites, and Wiki. On the document, Apple lists three possible replacements for each, such as the open source Apache HTTP server that its own Websites functionality was based on.
AppleInsider discussed the matter with our own sources not authorized to speak on behalf of the company, with them saying that in many cases, the Apple-mandated service wasn't as up-to-date as the open source version. As a result, users were replacing sometimes deprecated versions with newer ones. Further questions involving additional reasoning behind the move were not answered.
The move will make macOS Server less of a "plug and play" solution than it is at present. Instead of users setting up a service and figuring out how to deal with it through use, the installation process will basically demand at least a bare-bones level of knowledge from the administrator to get it to work right in the first place.