Enhance Server Security: Changing Default RDP Port and Enabling Multiple Sessions
When you connect to a computer (either a Windows client or Windows Server) through the Remote Desktop client, the Remote Desktop feature on your computer "hears" the connection request through a defined listening port (3389 by default). You can change that listening port on Windows computers by modifying the registry.
Start the registry editor. (Type regedit in the Search box.) Navigate to the following
registry subkey: HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\Terminal Server\WinStations\RDP-Tcp\PortNumber
Click Edit and choose Modify, and then click Decimal.
Type the new port number, and then click OK.
Close the registry editor, and restart your computer.
The next time you connect to this computer by using the Remote Desktop connection, you must type the new port
By default, Microsoft Windows 2012, 2016 and 2019 servers allow a single Remote Desktop session. If you have multiple administrators working on your servers and only one session is available you will take over another person's live session.