Adding the Firewall rule
We will need to unblock the port you choose first so let's get started, go to the start menu and open up Windows Firewall with Advanced Security and click "New Rule..." on the right hand side.
Leave the port as a TCP Port and the input the specified local port as the port you want to use for your RDP connections. We've chosen 3385 in this example.
Make sure you tick Allow the connection for this step and then make sure all check boxes are checked for the next step.
When naming, you want to choose something easy to remember just in case you ever want to change the RDP port.
Change the port in registry
Now we're going to actually change the RDP port inside of the registry editor.
Open the Registry Editor via the start menu.
Locate and then click the following registry subkey: HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\Terminal Server\WinStations\RDP-Tcp\PortNumber
You want to navigate your way through regedit until you have the file RDP-Tcp selected, then you will be able to scroll down and find PortNumber on the right hand side.
On the Edit menu, click Modify, and then click Decimal. Make sure you click Decimal BEFORE you change the value. We cannot stress this enough, change the option to Decimal, VERY IMPORTANT!
Type the new port number, and then click OK. Save the port somewhere safe so you don't forget it.
Restart/reboot the computer and you're good to go.