RDP issues from outside the domain

2016-06-08

Question

_{Wednesday, June 8, 2016 9:39 PM}

I connect to PCs at work through a SonicWALL. Been doing it for many years. No problems until I upgraded a 7 pro PC to 10.

Now, I can connect to the Win 10 box from anywhere inside the domain using RDP but can't connect from outside the domain through the SonicWALL. I get the login screen but, after entering credentials I get a black screen with the blue RDP tag at the top and an interactive cursor but the connection never completes. Eventually I get a timeout error and the 'attempting to re-connect 1 of 20' message (from the SonicWALL).

I have no problem connecting to any of the Win 7 boxes or the 2012R2 servers using RDP from outside the domain. Just the Win 10 box.

All settings are correct. All Domain Users, Domain Admins, and my own domain account are members of remote group. Port 3389 is open (obviously since I can rdp from inside the domain).

I've tried every suggested change that I can find on-line. No joy. Any ideas why this is happening?

All replies (4)

_{Friday, June 17, 2016 11:19 PM ✅Answered | 1 vote}

So the answer is.....

Windows 10 starts the RDP connection with TCP but changes to UDP. (Versions prior to 8 just used TCP.) The SonicWALL won't pass the UDP without being configured to do so.....BUT....Win 10 allows a GP setting at Local Group Policy > Computer Configuration > Administrative Templates > Windows Components > Remote Desktop Services > Remote Desktop Connection Client - named "Turn off UDP". Enable it on the machine initiating the session.

_{Thursday, June 9, 2016 5:25 AM}

Hi frmii,

Have you tried to use remote desktop connection in Windows 10 to connect the machine which is out of domain?

I suspect the issue should be related with the filewall settings.

By the way, have you contact the SonicWALL support?

In addition, please take a check with the network traffic, if possible, capture two network traces, one for Windows 10, which the connection not working, and the other under working Windows 7.

Regards

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_{Thursday, June 9, 2016 12:38 PM}

Did you check the SonicWall logs? They should tell you if it's the Wall.
Do you do an IP translation through the Wall from outside to reach the computers inside or do they have public IP's?
Start Wireshark on the troublesome W10, try to connect from outside. Do the port 3389-packets reach the W10?

BTW: Port 3389 doesn't need to be open when you RDP from inside the domain, only from outside.

Best regards, George

_{Thursday, June 23, 2016 8:11 AM}

Thanks for the update and sharing.