Apple has released macOS Server version 5.7.1. The biggest change is the announced elimination of many functions.
Here is an excellent macOS Server alternative. >>>
Apple is in the process of redesigning the Server App’s scope of functions, moving away from a simple management interface for many different server services to a program that is mainly used for device and user management, i.e. more interesting in an environment where many devices have to be configured. However, the corresponding services are no longer provided.
Apple no longer bundles open source services such as Calendar Server, Contacts Server, the Mail Server, DNS, DHCP, VPN Server, and Websites with macOS Server.
Whether this is bad or not is left to the discretion. Apple announced the change at an early stage and lists the corresponding alternatives. So you don’t necessarily lose the corresponding service – but the simple administration via a common interface is omitted. In macOS Server 5.7.1 only Open Directory, Profile Manager and Xsan Management remain.
All newly introduced management functions for macOS, iOS and tvOS can be found here in Apple’s support document. The Server App is downloadable via the App Store.