The server 2016 GUI does not provide a means to disable Windows Updates and by default the updates are set automatically download. There is a spot for updates in the GUI but it is a placebo. If you wish you can disable Windows Updates and run them manually at your hearts content, you need to do this via the sconfig text based applet.
Do the following. Start Powershell as admin and run the sconfig command. This is the server configuration text based applet.
Once you have run this applet option 5 is for Windows updates. For productions server the Manual option is probably the best choice.