RDS Connection fails with "An internal error occurred" RRS feed

  • Question

  • We have several users on a Windows 2012 RDS server. Recently two started having an issue logging in. They VPN to a Sonicwall firewall (which is successful...we can ping the server).

    When they try to connect using the Windows RDP client we are now getting "An internal error occurred". I cannot find out where details of this error are so It's VERY frustrating to try to fix based on "something went wrong" as the definition.

    I need to get this working ASAP. How do I track down where this is failing?

    Note: This is a Sonicwall NSA 250M firewall with sufficient VPN licenses. We can PING the remote server through the VPN tunnel but we cannot seem to get folders by opening Windows File Explorer and typing in the server IP (e.g. \\ It times out (and there are shares on that server so we SHOULD see SOMETING). 

    Is this a sudden firewall issue or something to do with RDP server licensing or something else? I have no clue where to even start investigating this.

    Client PC's are WIndows 10 Pro. These systems USED to work! Now, all of a sudden, we're getting this error when they try to RDP in to the server.

    Any help is greatly appreciated.

    Friday, December 15, 2017 11:00 AM

All replies

  • Hi,

    I suspect that firewall ports could be blocked, please try to telnet port 3389 (default RDS listening port) and 445 (SMB file share).

    If that's not the case, you may try to analyze the traffic with Network Monitor or other tools.

    Best Regards,


    Please remember to mark the replies as answers if they help.
    If you have feedback for TechNet Subscriber Support, contact

    Monday, December 18, 2017 9:29 AM