Cant join the same match whit the same internet

Assuming you're both in the same household using the same internet service, I'll venture a guess that you're both showing the same external IP to the game servers, which can be problematic.

Getting a static IP, using UPnP, or using a VPN are some options that may work. Static IP is the surest way, but most expensive. You may be able to just use UPnP, which is free to you, but I'm not sure that will work. VPN you can usually find for free or really cheap, as least to try it to see if it helps.