N solution. Please answer. Official affects private servers

Hello. how are you? I bought the original game (Diablo II LOD). I installed it on my computer, then I formatted the computer, but changed the username (which it asks you when you format the computer). When I do this, on private servers (at least three servers), every time I stay in a game for five minutes, the game asks me for the password again, not only that. I can’t send or receive private messages after those five minutes.
After using the original game with the computer formatted, the game restricted my “Keygen”, but that was already solved, it was to add credit if it provided more information.
Long story short, having used the original Diablo II Lord of Destruction game ended up screwing up other servers that I host frequently. Please, need help.

I await any response. I beg you.

Thanks so much.