Trying to port forward for friend to join our personal minecraft server

My friends and I have been trying to allow port forwarding so our friend in another state can join our server. in the router settings, we open the port that the minecraft server is on and change the port in the minecraft server properties from the default to what the world told us was the port. 

I am on the same network as him, and I type in the internal IP for his computer and the port and am able to join. our other friend is on the modem/router (a seperate device) and is trying to join through the port. He is not able to. I checked on a port finder site to see if the port is open and it says it is closed. 

Any help would be great, if its confusing im sorry. 

The netgear router is a RAX29