By default Windows server allows only a single session to be connected remotely to the server. You can change that by allowing two session to be connected on the same time.
1) Press the Windows Key + R then type MMC.exe
2) File -> Add/Remove Snap-in -> click on Group Policy Object -> Add -> Finish -> OK
3) Double click Computer Configuration -> Administrative Templates -> Windows Components -> Remote Desktop Services -> Remote Desktop Session Host -> Connections.
4) Set the Limit Number of Connections to 999999
5) Restrict Remote Desktop Services users to a single Remote Desktop Services session = Disabled
Now you can access the Server remotely with two Sessions 🙂