Can’t forword the ports needed

Hello there, last night me and my friend found about Celeste Project and we got realy exiced since we were a fan of AoEO. We installed the game as guide told us and game works perfectly but without multiplayer. We tried multiplayer guide to forward the ports also closed firewall on pc and router, enabled upnp and used launcher helper to make all options valid. Still no matter how many times we checked ports via port checker it was a failure and when we tried to play together, we always ger the error “player xxxx doesn’t exist ...”.

Finally we tried dmz mode and it actually worked for me but my friend’s ports was not forwarded even tho his ipv4 was dmzed. No matter what we do we couldn’t figure out a way that worked for him and we both realy hate hamachi. It would be my last resort to try it and I realy want to avoid using it if possible.

Right now we realy don’t know what to do, so if anyone has any idea that might help us, we realy would appreciate it.