I think ı got ip hacked

So, ı and my friends were playing minecraft peacfully. We were buliding stuff. And some time later some weird things started to happen. My and my friends op dissapeared thewe started to die servers gamemode started to change and ot was writinf server so i tried to ban server and it worked and then a user named server_ joined i banned it but now a new user joined. I created a new server and the same thing happened ı createn a whole new aternos account and it didnt work. Now he was entering the server as my friends and me. He was straling ur accounts. We opened new accounts but it wasnt working. İt kept stealing. I activated whitelist and it kinda worked ı saw from tje console that he was trying over and over to enter the server. And then he stole our acconts again so the whitelist didnt work. The cracked is open becouse me and my friends use tl legacy to play minecraft. I dont now if my launcher or aternos got hacked but now ı cant open servers from aternos. Please help me. The hacker keeps joining stealing our accounts and ruining our bulids. We couldnt solve it no matter what.

Quote from Anrah

You didnt get ip hacked lol, you can just log into other peoples account using Tlauncher

So how can ı fix it ?

Quote from Anrah

You cant do much really except maybe adding the register and login plugin onto your server so that you will need a password to actually move around and do stuff

I added it but it hackes my account before ıı even enter the game and sets a pass. But ım gonna use a diferent method a few hours later. Im pretty sure ıt will get rid of it wish me luck.