port forwarding

Hi, I've had some problems port forwarding for a while but I've finally decided to figure out why it doesn't work. Recently, we upgraded to cox's panoramic wifi which is a 2 in1 router and modem. When i type in the default gateway it sends me the the usually website however it tells me I must port forward on wifi.cox.com. When I do this i went through the "much easier" port forwarding process they set up but when I go to try and use my server, the ip doesn't work. Locally I can access my server but using the public ip doesn't work so I can't access it from outside. I hope someone can help! THX!

Idk if this would help but I'm trying to make a minecraft server.