How to resolve the issue “Remote Desktop Disconnected” or “Unable to Connect to Remote Desktop (Terminal Server)”

One of the recurring issues seen in product support is why a client cannot connect.

Specifically, errors such as “Unable to RDP,”  “Remote Desktop Disconnected,” or “Unable to Connect to Remote Desktop (Terminal server)”  are common problems that we have seen come up in product support.

This article summarizes the various causes for Terminal Server Client (Remote Desktop Client) connection failures and how to fix them.

Some of the commonly seen Symptoms (order of frequency):

1. You may be limited in the number of users who can connect simultaneously to a Remote Desktop session or Remote Desktop Services session
2. You may have a Port assignment conflict
   • Associated Error messages:
     Remote Desktop Disconnected.
     This computer can’t connect to the remote computer.
     Try connecting again. If the problem continues, contact the owner of the remote computer or your network administrator.
3. You may have an incorrectly configured Authentication and Encryption setting
4. You may have a corrupted Certificate
   • Associated Error messages:
     Remote Desktop Disconnected.
     Because of a security error, the client could not connect to the remote computer.
     Verify that you are logged on to the network and then try connecting again.
   • Associated Event IDs:
     Event ID: 50
     The RDP protocol component X.224 detected an error in the protocol stream and has disconnected the client.
   • Additionally, you may also see this error message:
     The client could not establish a connection to the remote computer.
     The most likely causes for this error are:
     1) Remote connections might not be enabled at the remote computer.
     2) The maximum number of connections was exceeded at the remote computer
     3) A network error occurred while establishing the connection
     4) The remote computer might not support the required FIPS security level. Please lower the client side required security level policy, or contact your network administrator for assistance.

We have provided step-by-step documentation on how to fix these issues in the following articles.

Main article:

Troubleshooting RDP Client Connection problems:

http://support.microsoft.com/kb/186645

Please refer to any/all of the following articles based on your Remote Desktop Session Host Server OS:

• Windows Server 2003: http://support.microsoft.com/kb/2477023
• Windows Server 2008: http://support.microsoft.com/kb/2477133
• Windows Server 2008 R2: http://support.microsoft.com/kb/2477176

More Information:

1. The following posts discuss symptoms 2 & 3 from above caused due to port assignment conflicts and/or encryption level settings:
   • http://www.techsupportforum.com/networking-forum/file-application-sharing/49577-unable-use-remote-desktop.html
   • http://www.computing.net/answers/windows-2003/unable-to-rdp/8257.html
   • http://serverfault.com/questions/47356/remote-desktop-disconnected-error-trying-to-connect-to-a-windows-xp-computer
2. The following article from ehow.com talks about how to troubleshoot a remote desktop disconnected problem but only covers very basic issues.
   • http://www.ehow.com/how_6574577_troubleshoot-remote-desktop-disconnected-problem.html
   
   Ex: It asks you to check if the computer you are connecting to is powered ON and/or not in ‘Sleep’ mode.
   It also talks about some of the basic settings to enable remote desktop sessions which are covered in symptom 1 above.

Additionally, we have more symptoms documented under the following article:

Troubleshooting General Remote Desktop Error Messages

http://technet.microsoft.com/en-us/library/cc780927(WS.10).aspx

Note: This is a work in progress and we will constantly be updating these articles to reflect the latest issues and how to fix them.