Apple used to have a fantastic application called OSX Server (now called MacOS Server) which allowed you to run a full server from any OSX computer. A server can allow you share files, run your own email or web server, remotely connect in to your office etc. OSX server was particularly powerful running on a Mac Mini. With OSX Mojave Apple killed off OSX server, but it is still possible to download an older version from Apple that still works. Here’s how.
Firstly you will need a Mac running an older version of OS X. This is the Mac you will run OSX server on. I used El Capitan but any version prior to Mojave will work.
If you try to ‘purchase’ OSX server on this older OS it will say that MacOS Server is not compatible with the older OS. The only way to purchase Server is to be running Mojave. So you will need access to a mac running OSX Mojave to make the actual purchase.
Once you have purchased Server you can then download the older version to your older OSX.
On the Mojave OSX computer login to the App Store and purchase a new version of OSX Mojave. You don’t need to download it. You can cancel as soon as it starts to download.
Now use the computer with the older version of OSX and login to the same iTunes account. In the App Store click on the little tag that says ‘Purchased.’ MacOS Server will now appear and you can download an older version that works with your older OS.
You should now have a working version of OSX server that includes all the features like VPN, FTP, Mail server and everything else that Apple removed from the Mojave version of OSX server.