Are you adjusting the unique username and the corresponding password information for each character's game account? It is possible that you are only using the login information from one of your character's game accounts to log in multiple times even though you have three accounts set up.

No, i have 2 different Ashita windows opened, and I input Silma as username in one, and Silmb as username in the other.

I just tried deactivating my router's firewall, windows defeder firewall and my AV. Doesnt work
I still think i need some NAT rules on my router (its my last chance) but i dont know which ports to forward so that doesnt help