Hello.

As far as I can tell, the client side (QuickOPC) is working as expected. This is an error given to us by the COM/DCOM infrastructure, and it indicates what it says - and it relates either to the target OPC server, or the OPCEnum service on the target computer. The client code code cannot do much about it, except reporting and retrying.

Hints:
- Check the target computer Windows logs around and before the time the problem occurred.
- Check how the OPC server is configured in DCOMCNFG. Is it set to run as a service? If so, under which user account? If it is a specific account, is it correct one? If it is something like "Interactive User", or "Launching User", then it could be a problem too, because these can change depending on either who is logged in (or nobody), or who is the OPC client (which can change).
- Check the same in DCOMCNFG for the OPCEnum service.

Best regards