How to setup and troubleshoot Remote Desktop Connection (RDP) issues ?

There are a couple of general steps to successfully set up a Remote Desktop Protocoll (RDP) connection to your computer, as outlined below:

1. Setup your computer - to allow remote access to your computer, navigate to Control Panel > System and Security > System > click Advanced system settings > Remote tab > tick "Allow connections from computers running any version of Remote Desktop"

2. Allow RDP through your software firewall - make sure that Remote Desktop connections are allowed through the Windows firewall (or any other security software you may be runnig). For Windows Firewall, navigate to Control Panel > System and Security > Windows Firewall > click "Allow a program through Windows Firewall" > locate "Remote Desktop" and tick to allow it for both private and public networks.

3. Allow RDP through your NAT router - most recent internet connections include some type of NAT router/gateway that allows for multiple clients on your home network. Such home network serves IPs that are not routable on to the internet (usually in the 192.168.x.x range). Anyone connecting to you remotely needs to connect to the external IP of your network (the one assigned to your gateway/modem/router), and then, your router needs to forward the correct RDP port to the correct computer. RDP uses port 3389 by default. You need to configure port forwarding to forward port 3389 from remote connections to the correct internal IP address of your Remote Desktop computer.


Troubleshooting:
If you can't connect to the RDP computer, it is either a port forwarding issue (your router), or a firewall issue (allow RDP connections through the Windows Firewall)

If you can see the login dialog, however you get a login error, note the following bug in Windows 7: If you change your Windows login name, it does not change in RDP - try with your old Windows login name (and the new password)!

Notes:
For security reasons, to reduce the number of attacks, it may be a good idea to change the RDP listening port from the 3389 default to another high port number in the dynamic range (49152 through 65535). Open the Windows Registry Editor (type regedit in the Start menu search field), and navigate to:
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\TerminalServer\WinStations\RDP-Tcp\PortNumber
After changing the PortNumber from the default 3389 (and rebooting for changes to take effect), any client connecting to you must also specify that new port number as: x.x.x.x:nnnn (where "x.x.x.x" is your external IP address, and "nnnn" is the port number)