We have an Xcode Server, working perfectly in our local network.
Now we also want be able to access this Xcode Server when working remotely.
The problem is that the network has a dynamic IP.
What is the best way to make Xcode server available over the web to Macs outside our local network?
I use the free DDNS service from Dynu Systems. They have an API which allow you to update your IP address as it changes.
They provide a updater app that will make the updates for you, or you can check out Dynumite on the Mac App Store. It lives in your menu bar and updates on a schedule you set. (Full disclosure: I wrote it.)
Unfortunately Xcode Server no longer allows you to specify your own SSL certificate, so you will have a notification when accessing your server remotely using the browser, but Xcode should be fine and display your server (with FQDN).