With the new release of macOS High Sierra (10.13) apple performed upgrade also to Server app. First of all Apple suggest to update to macOS Server 5.4 after you upgrade to macOS High Sierra.
Unfortunately this update gives important changes to the services we are used to manage (see below for app changes). In fact, Caching Server, Time Machine Server and File Sharing advanced options are now built directly into macOS. This means that you can not managed these services anymore from the CLI (bad thing!). You’ll find all the settings in sharing preference panel.