friend can't connect

i created an aternos server the other day, and me and three other people play on it. one of my friends was able to get on the first day but now can't get on at all and gets a message that says "io.netty.channel.ConnectTimeoutExcetpion: connection timed out" when trying to log onto the server. me and the two others can log on and play fine, its just the one person that cannot log on.

we've tried both and he still can't log onto it

the google public one

he didn't before but now he can't connect to any