Avatar of James St. John
James St. John
Flag for United States of America asked on

SQL Server connection problems with VPN

We have a C# .NET application written against FW 3.5 that connects to a SQL server using Windows authentication on our local network.  The systems running the app are using Windows 7 SP1 or Server 2008 R2 SP1.

To provide support to some of our clients, we sometimes have to VPN (PPTP) into THEIR network - separate DNS servers, different domain name, IP subnet completely different from ours.

Whenever we're connected to a client's VPN, we get the following exception when we launch our application: System.Data.SqlClient.SqlException: Login failed for user ''. The user is not associated with a trusted SQL Server connection.

We don't understand this.  We're attempting to connect using credentials from the local domain to a SQL server on the local subnet.  Why are we getting this error?  What can we do to eliminate the problem?

We did some additional testing.
- Windows XP: problem does NOT occur.
- Windows Server 2003: problem does NOT occur.
- Windows Vista: problem does occur.
- Windows Server 2008: problem does occur.
- Windows 7: problem does occur.
- Windows Server 2008 R2: problem does occur.

-- Jim
Microsoft SQL ServerVPNWindows Networking

Avatar of undefined
Last Comment
James St. John

8/22/2022 - Mon
Rainer Jeschor

Log in or sign up to see answer
Become an EE member today7-DAY FREE TRIAL
Members can start a 7-Day Free trial then enjoy unlimited access to the platform
Sign up - Free for 7 days
Learn why we charge membership fees
We get it - no one likes a content blocker. Take one extra minute and find out why we block content.
Not exactly the question you had in mind?
Sign up for an EE membership and get your own personalized solution. With an EE membership, you can ask unlimited troubleshooting, research, or opinion questions.
ask a question
James St. John


The information contained in link to sevenforums.com worked perfectly for me.

Why Microsoft didn't make the setting on option on the VPN adapter settings dialog is anyone's guess.  

Also - if anyone turns on the "Allow other people to use this connection" option when setting up the VPN connection (I DON'T), I believe location of "common" rasphone.pbk is
Access to this folder is usually restricted, so as you drill into the folders Windows will (at some point) prompt to allow access.
Experts Exchange is like having an extremely knowledgeable team sitting and waiting for your call. Couldn't do my job half as well as I do without it!
James Murphy