So few apps would use only one port. FTP uses 2 and so on. Time to ask this unknown app's author for more detail about port numbers.
I'm trying to port forward a application , i have 1 router Tp-Link TL-WR740N connected to my PC, i tried to port forward the app but not working , i see i got a private ip adress , is like i have 2 routers/Nat (i guess) , but i don't , how do i resolv this? , here is some screenshots.