Will my achievements vanish when I change my name?!

So my friend owns a server from Aternos. He plays there, me and also my other friend. I completed many achievements and I want to change my name but my friends told me that once I change my name all of my achievements will be gone! I really want to change my name but I dont want to loose all of my achievements. The server is on whitelist and only my friend has the control of it, he starts the server, turns it off and that kind of stuff... So is this thing with the achievements true or what? Please help me!

-also sorry for my bad grammar im from Slovakia

Quote from Roman

Which server software is the server running?

Has the server cracked mode enabled?

So i dont know exactly what do you mean by software can you plase type it more specific and for the cracked mode I think you mean If are there any players without original minecraft. So im the only one that has original minecraft an my 2 other frieds have tlauncher

Quote from Julian

Then yes, changing your username will reset your inventory, advancements etc.

nooo