Hello,
I found the issue. My Python script had mistakes after I changed it therefore the server never started.
Secondly, when you re-build the URCap, the changes apply to the URCap but not to the Python script of the URCap.
You either have to delete URCap from URSim and re-built the URCap again or you have to change the Python script in /home/ur/ursim/ursim-5.9.1.1031110/GUI/felix-cache/bundle
Thank you