I have made more tests, in an attempt to reproduce the remaining problem. The tests used two newly installed computers (client side + server side). On the client side, I was using both QuickOPC, and Softing OPC Client. I have tested many different security configurations, and in all cases but one, the results of QuickOPC and Softing OPC Client were the same - i.e. they either both worked fine, or none have worked.

There was one configuration under which the Softing OPC Client was able to enumerate the OPC servers on the remote computer, but QuickOPC not. I have investigated the problem in this case, and fixed it in QuickOPC. It is not precisely equal to your situation, however, because it only affected the browsing for OPC servers, but not the actual connection to the remote OPC server. Due to the code logic, however, I can foresee that it actually could be the same thing you are experiencing.

When you get a chance, can you please download the recent build from our Web site (5.12.1205 or later), and retest?

Best regards