How to determine what application is using a port and blocking its usage.

Several of the erwin dm applications such as the license administrator, the mart server, and the web portal all use ports to communicate with the DBMS, the web browser, and/or the applications themselves.  If a port is being used by another software application, that would interfere with the usage of the erwin application.

For example, erwin data modeler needs the port 27000 to be open on a client machine in order to obtain a license from the license administrator.  It may be possible there is an application already accessing port 27000 on your PC and that is why the port is not open and erwin cannot obtain the concurrent license.  

The user could go to a DOS prompt and run
     netstat -ano
which will show all open ports along with the associated process id (PID).

Then you can go into the windows task manager and add a field for Process Page Columns or PID

And then you would see which application is already accessing the port 27000 and blocking erwin dm's use of it based on the PID.

Then you could shut down that other application (if not critical) and that would free up the port 27000 for use by erwin dm.