If you use remote desktop services 2012 then by default when you connect of the Web Portal it uses port 443 (Secure HTTP). This is fine if you do not not have any other servers that require the use of the 443 port. Unfortunately in the environment I was working on – the client had Exchange 2010 so was using 443 for OWA. I needed to change the default web access for port for server 2012. Here is how.
Most Administration in Server 2010 is done from server manager, however we cannot administrate the Remote Desktop Gateway App here. If you go to the tile screen start typing remote desktop and you will see the app, then launch it.
Once done you will see your server name, right click it and select properties and you will see the screen below. Go to Transport Settings.
You will see the HTTPS ports is at 443 by default. Change it to the port you desire, I use 4443. You will then be prompted that all connection will disconnect and the service will restart. This change is now in effect, remember to also change any NAT settings and redirects on your firewall accordingly.