After reading all of your comments, i spent the whole day on it and finally managed to port forward, i tried UPnP, DMZ, firewall settings but nothing helped, at last i figured out the external ip, server ip, ports, application name and all that stuff and add a total 7-8 port rules for modern warfare and finally got OPEN nat type. THANK YOU everyone who spent their time replying to the post and helped me figure out the problem 😇 really appreciated