As far as I know the loopback adapter always has to be running on the host machine, so I would suggest removing the loopback from your gaming PC first and then create a loopback on your server. However, you might need to enable ICS on your host machine as well for this to work properly. Go to the control panel of your server, go to network connections and right click the adapter you're using to connect the server to the web (not the loopback!). Go to the advanced tab and tick the option called "allow other network users to connect through this computer’s internet connection" and in the drop down menu below specify that you want to share the connection with the loopback adapter. Let me know if this worked for you.