Spring RTS Engine

i brought my laptop over his house to play some BA and i go to log in this morning and i got this message "Login failed: You are banned from this server! (Reason: banned till christmas for trying to nazi autohosts with multiple accounts). Please contact server administrator." we both have ...

i need to know specifically what the problem is and how to fix it

ok for some reason when i try to host a game with me and my friend, i get the message:

"Warning : [my friend's name] doesn't support NAT Traversal"

idk what this even means
i THINK i opened my port correctly, but how can we get this to work?