Network port not listen while running game

I downloaded the Shootout Demo to try networking.
I packaged it to window standalone and ran two instances in same PC. That was work!
It can create and join Session.

But I try to run instances in two PC(,, Create Session Find Session
I would found no session in
I already set the port forwarding,
and i use some port checker that show the port is open

However, i checked my game in process that show the it used 27015, not 7777!

" that show the it used 27015, not 7777!"

if u open 27015 then does it work?