FTP server is gone from High Siera OSX Server
It is gone finally… [macOS Server 5.4 changes in High Sierra you need to know about!])https://www.imore.com/changes-macos-server-54-high-sierra)
File Transfer Protocol (FTP): A longtime a security risk, for example for sending password information in clear text, FTP support will be removed from macOS server if you upgrade.
As my xeros printer/scanner suppors only ftp or samba(which is much much slower than the ftp) I have to run my own ftp server in my mac mini.