I have tested what you said and I didn't succeed adding a virtual port. I have also used DynDns and other dynamic DNS service, but it's not working. This could mean the software is not supported on newer versions of Windows or there are bugs in the application.
If you have an older version, I recommend downloading the latest one through the following link: http://ftp.opengear.com/download/portshare/windows/
Note: Reinstalling the software using the latest version could fix this problem.