So I setting up an old Desktop PC as a Windows 2012 R2 Essentials Server.  I wanted to use WiFi to set it up as I am not near a network port, but every time I enabled the disabled WiFi adapter it kept disabling itself again.  Even using a USB WiFi card didn't work so a little poke around and it was a simple fix to get working.

Fix:-

You need to install the Wireless Lan Service in Server Features.

So Run Server Manager -> Manage (Tab) -> Add Roles and Features

Click through the wizard until you get to Features Section and tick "Wireless Lan Service" (near the botttom).

Might need a restart.

OK but wait the WiFi adapter is still disabled.  Quick check in Services:-

Server Manager -> Tools (Tab) -> Services

and I noticed the WLAN AutoConfig was not started.  Start this and bingo you can now connect using WiFi.