For context, the majority of server features were removed in macOS Server 5.7.1, with a few features migrated to macOS High Sierra and the remainder left to be handled by open source alternatives. The initial announcement from Apple was discussed on HN in 2018. [1] [2]

[1]: https://support.apple.com/en-us/HT208312

[2]: https://news.ycombinator.com/item?id=18113147