I searched through the forum and read the manual but could not find the solution for my problem, therefore I open here a new post.
I am member of a clubstation (DK0RUS) inside a company. Our shack computer is part of the companies network and probably that's the root cause of the problem.
What is the problem?
I tried to connect to several DX clusters, but never had any successful connection.

Is there a special port or some basic access rights necessary for the clusters? At home I have no issue connecting to any cluster.
OS is Win7 and I installed the latest release of Log4OM. I also tried the Win7 options to start it as admin and even XP compatibility mode.
First we installed it in the Program(x86) folder, in a second try I installed it right under C:\ to avoid local access right problems.
Any useful hint is welcome!
73
DL8CQ