Multiplayer not working

*What I expected to happen was
Join my server (from aternos(i've tried other server like hypixel too)

*What actually happened was
I couldn't connect and I got the classic error message; internal exception java.io.ioexception an existing connection was forcibly closed by the remote host

Most of you probably wont be able to reproduce

I have also tried it on another computer on the same network, didn't work.