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Setup RDP for multiple computers on LAN

What is RDP?

A lot of people use the default Remote Desktop application provided with Microsoft Windows.  I am not going to get into the details of Remote Desktop Protocol (RDP), however a Google search turns up the following:

Remote Desktop Protocol (RDP) is a proprietary protocol developed by Microsoft, which provides a user with a graphical interface to connect to another computer over a network connection. The user employs RDP client software for this purpose, while the other computer must run RDP server software.

Setup RDP to work on Multiple computers on your LAN

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The issue is that when you have multiple computers on your Local Area Network (LAN), and two of them are using RDP.  RDP uses port 3389 by default to connect to computer.  You must setup port-forwarding so your router knows which computer to send the connection string to.  When you have multiple computers, connected to the same router, the router must be able to distinguish which computer the RDP request is going to (when attempting to connect from outside the network).  When you are inside your Local Area Network (LAN) and you want to RDP to a computer, you can just use the different IP addresses the router has assigned to the computer (192.168.1.12, 192.168.1.13, etc.), but from outside the network, you will only have IP address (in most cases).  Therefore, the router must know which computer to send the request to based on PORT NUMBER.
The rest of this article will show you how to configure your port number and forward the connection request to the correct computer.

One computer can use the default RDP port number (3389).   The router will know to send all RDP requests for default port to that computer.

Any other computer, you must change the default RDP port, and change the router settings to forward requests to the correct PC.

To change the Port number:

  1. Open the Windows Registry Editor.  On the Start menu type “regedit” and hit ENTER
  2. Navigate through the folders on the left to find the RDP-Tcp folder in this path: HKEY_LOCAL_MACHINESYSTEMControlSet001ControlTerminal ServerWinStationsRDP-Tcpregistry
  3. Double click PortNumber in the right pane and then select Decimal for the Base type

We’re looking to change the DWORD (32-bit) Value for PortNumber:.

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The default value is 3389 but you can change this port number to anything.  In the figure above, the port 3388 is selected.

The default port for this computer has been changed.  Now you may need to configure Windows Firewall or any other Firewall to create rules and  allow traffic to pass to the computer. (Not covered here)

Now need to assign port number in router settings.  The next task is to point the new port number to the specific internal IP address so that outside requests are understood properly.

  1. Open browser and navigate to router login page: http://192.168.1.1.
  2. Look for Port Forwarding section
  3. Enter new port number and local/internal IP address of the computer

To find the local IP address, run command prompt and use “ipconfig”, or you can get this information from the router page.

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Local IP address is listed as IPv4 Address

Now you should be able to connect to the computer using the new port assigned. Open Remote desktop from a computer outside the network and enter the information in the following format : [COMPUTER_IP]:[PORT]

Example: 74.212.14.137:3388

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