Is UPnP enabled on you an your friends routers? If not you could enable it on your router by Launch a web browser from a computer or mobile device that is connected to your router's network.
If you can't figure out how to do that there's another way first, launch the game though steam or launch waw without plutonium and download 2 things waw lan fix and Hamachi start a sever on Hamachi have your friend join the server than create a lan game than have the person who isn't the host join the lan game and then set the server settings to whatever you finally you should be able to play.
here's video instructions for method 2: https://www.youtube.com/watch?v=3gt8mcevY2g&t=84s&ab_channel=MasterBeef96
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