yeah just for record's sake.
, I use DMZ feature (found in 99% of routers) set it to enable. And im able to host. It opens all ports. It's how I've opened ports for all apps and other games in the past and has worked and continues to work. Yet, not only your port tester, but other port testers I've come across like emule's also detect is as CLOSED but the port is indeed open and the emule client connects without further hassle.
I don't use portforwarding, never have.. in my opinion is too much hassle, some routers require to select either UDP, TCP, both, then select a range whereas DMZ is just enable/disable and pick your computer's name from a dropdownmenu list.
and even then, i've come with routers that even after portforwarding the port still is closed