salam alikom i will show you how to open port in DLINK 2750U and activate this port at first you tape in mozilla:
go to 192.168.1.1


write your password generally admin


go to internet setup


click advanced


click on port forwarding


click add


write your name server


shedule always "always"


write the ip that you want port forwarding


write your port number (tcp/udp)


then click apply.


now we created the port

to activate it we must go to DMZ


click enable DMZ


write ip of the port forwarding or 192.168.1.1.

the apply and it's done.

and here is a video to show how to:
h**ps://youtu.be/A1mZ14MMebg