Apple has released macOS Server 5.4 with support for APFS volumes and new restrictions, payloads, and management commands for Profile Manager. The update now hides Open Directory and Software Update Service by default, integrates Caching Server, Time Machine Server, and File Sharing advanced options into macOS, and enables you to migrate Server data from a volume with OS X 10.10.5 Yosemite and Server 5.0.15 or later. Changes to Profile Manager include new supervised-only Classroom restrictions in iOS 11 to allow managed class behavior for unmanaged classes on supervised devices, new payloads in macOS (Extensions, Smart Card, and System Migration),
and a new AirPlay Incoming Security payload for tvOS.
Note that you'll need to manually install macOS Server 5.4 as updates aren't automatically installed (even if you've selected other apps to update automatically from the Mac App Store). macOS Server 5.4 now requires macOS 10.13 High Sierra at minimum. ($19.99 new, free update, 194 MB, release notes and security content, 10.13+)