More exactly, that message comes when the number of moves increases (typically when the queen enters in action).
If I run my engine from the command prompt and enter the same position, I get a best move, after one good minute, but I get it.

So technically what does means that "connection stalls", and how to solve that? Should I break my loop in several parts?
A last thing: I can see in the task manager that the engine uses a constant small memory (1,3 Mb) and 25% of the processor.
Thank you for your attention.