lotus domino server/notes client problem

Ello,

sometimes i can't connect to the domino server when LNS is running. I'm logging all the rules that i set to block but i can't see anything in the log when it happens. In application filtering, the .exe files related to the client are authorized. When I close LNS, the notes client can communicate with the domino server, otherwise not.
The strange thing is that when I close lns and open it again everything is fine.

Well it happens rarely, but i dont want to run to users in random times because of this.

Thank You!