Hi everyone.
As a game developer I have the best solution for your issue since I have dealt with this issue myself in my servers in past.
Let's straight ahead move to the solution.
Instead of banning them from entering the server, break them and thier mind psychologically.
My psychologically, I mean make them fed up, tired and annoyed.
Q. How to do that ?
A. Punish them by thier IP, everytime they join the server.
Q. What kind of psychological punishment ?
A. Good question, we punish them by simply doing 3 things.
1. Fade thier screen to black permanently.
2. Gag them permanently.
3. Set their next attack time to very large amount such as 99999999999.
Note. The above 3 things can be easily done by a simple plugin, but keep in mind that the victim should not get the idea that he is being punished. You gotta frame it in such a way that for the victim it makes him feel like something is wrong with his game or something similar. To that do not include and sound and chat messages when you punish the victim.
That's it.
This solution is 100% tested and it works.
If you need the above plugin then I can provide it too. Just dm me server manager. 😎
Thank you for your time.