Custom Web Service With InfoPath

I am facing issue with accessing a custom web service deployed to _vti_bin of SharePoint Site. The web service is being called from the InfoPath 2007 browser enabled form tem开发者_Go百科plate. Everything works fine if the call originates on the same machine as the web service host. It's an anonymous web service with no auth needed.

When I access the form from an external environment, it throws "Error accessing data source". There's nothing in logs or event viewer.

Any idea is welcome as it is becoming cryptic considering there are no logs.

In the end, point number 2 in the following post served as the solution - http://sharepointconnoisseur.blogspot.com/2011/04/how-to-resolve-401-unauthorized-error.html