Assign number of processors to a Comsol server

Hi,
the option -np sets the maximum number of processors that Comsol is allowed to use. When Comsol is started in server mode this option seems to be ignored.

For example Comsol server is started (allowing one processor only): comsol server -np 1
Then an instance of Matlab is connected to this server and a model is solved in a certain time. Now I try the same thing but allowing Comsol server to use two processors: comsol server -np 2
Solving the same model takes about the same time to finish. So -np doesn't seem to influence the runtime.

Is there another way to assign processors to a Comsol server?

Best regards