Resolving Remote desktop disconnected error : Port assignment conflict

When the default RDP port, port number 3389 is assigned to some other application on the Remote Server, the client fails to establish a remote connection. Instead, it results in a remote desktop disconnected error due to the conflict in the port assignment.

Steps to resolve "Remote desktop disconnected error" due to port assignment conflict

• Determine which application is using the same port as RDP :
  • Open command prompt on the Remote Server and run the command netstat -a -o
  • In the displayed information, look for port number 3389 and identify the Process ID in the entry.
  • Use the command tasklist/svc to find the application corresponding to the above Process ID.
• Change the port assignment for the application.
• If the port assigned to the application cannot be changed, the port assigned to the RDP can be changed by editing the registry.

  Note : Making changes to the Windows registry is generally not recommended. Unless absolutely necessary, it is advisable to keep the RDP port unchanged.

  • Run regedit on the remote server and locate the following registry subkey :
    
    HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Remote Desktop server\WinStations
  • Select the connection under the WinStations key.
  • Double click the PortNumber registry entry and modify.
  • Click OK to save the change and close the registry.
• Restart the Remote Desktop Services (RDS) service for the port assignment change to take effect.
  • Open the Services snap-in on the Remote Desktop Server. Navigate to Administrative tools >> Services.
  • Right click Remote Desktop services and select Restart. If prompted to restart other services, click Yes.
  • Check whether the status of RDS service displays 'Started'.
• Verify RDP port assignment has changed
  • Open command prompt on the Remote Desktop server and type the command netstat -a
  • Check the displayed list for the port number assigned to the RDP and verify.

Verify listener on RDS is working using any of the following methods :

The Listener component is responsible for establishing and accepting new RDP client connections. It is important to ensure that it's working properly and is available.

Verify the listener on RDS is working using any of the following methods :

• Establish a remote connection from an RDP client to the Remote Desktop server
• qwinsta tool to view the listener status on the RDS
  • Type qwinsta in command prompt
  • Check if the state of RDP-TCP is "Listen".
• Netstat tool to view the listener status on the RDS using the command
  netstat -a
• Telnet tool to connect to the RDP port on the RDS
  • Type telnet rdpservername 3389. Use the server name and port number as configured in your environment.
  • The listener is working if telnet screen opens.

Meta-D: When port number 3389 is assigned to some other application on the Remote Server, the client fails to establish a remote connection. Resolve it by reassigning the port.