InfoPath Dev

Hi, I have a form that connects to a backend SQL database via a ODC connection configured on a windows 2003 server. The connection works when the form is opened on the server. However, when connecting to the form via a VPN connection on a client machine that is not a member of the domain, the connection fails, giving the following error:

The query cannot be run for the following DataObject: CONNECTNAME
InfoPath cannot run the specified query.
InfoPath cannot connect to the data source.
InfoPath has encountered an error. The operation failed.

I have hit the forums hard over the past couple of days and have not found a resolution for this. Here are some things I have enabled or verified:

Digital signature are enabled.

Form is configured to Full Trust.

Template has been signed and has a valid Certificate.

Domain under preview section is configured as http://domaincontroller

 Any help would be greatly appreciated

Have you verified the IE security settings?

They would need to have domaincontroller set in their Local Intranet or trusted sites zone for data conenctions to work correctly.

 Have you looked at Database Accelerator (DBXL)?  Sounds like you have a fairly complex solution and DBXL web services make things so much easier and performant, especially with VPN and remote users.

I had the domain controller set as a trusted site, so I moved it to Local Intranet and I had the same results. 

You are right, I need to test the database accelerator. I've read some of the documentation and I can use it's features in many ways.