All servers kick my friend out of it but i can join in and play normally

so every time my friend joins into a server, his screen either goes black for about 30 seconds and then kicks him out, or he can move normally (however i cannot see him moving) but couldnt open the boxes and gets kicked out about 30 secs later. the message says "lost connection; disconnect" how can he fix this problem pleaseeee

edit: he just tried using my account to play on his mac but they same thing happened.. so it seems to be the problem with his mac or ip but not his account??

Quote from ediee2602

its probably an internet issue

i think it's not because of the internet 😢 he can play normally in those big online servers but not the ones built by aternos.. he also tried flushing the DNS thing and changing ip but none of those work