I just want to host a Minecraft server

Okay, so I've been attempting to host a minecraft server for me and my friend from Brazil. I KNOW my hardware can handle it, I can log onto this server, everything works as intended. But my friend cannot join. After hours of troubleshooting, I have determined this is either my router's fault, or Cox's. Either way, I need this fixed. I logged into my router, was directed to port forwarding, put in the port number for Minecraft. Simple, right...? Except that it's NOT, because my friend cannot log on. No matter what, their connection times out completely and they cannot join. And the issue is not on her end, because we both have joined other servers and realms with little trouble. On top of that, I've used tools that check port openness...guess what? CLOSED. ALL OF THEM. This is absolutely absurd. Please tell me what I can do. I literally just want to play a video game with a long distance friend.