Unable to connect to world

Greetings, aternos!

Did you know why my friends can't join my server? Only 1 of my friends can join the server, they said they always seen "unable to connect to world" screen, I've been planning to make Survival Multi Player with my friends, can you help me?

By the way, my minecraft server is bedrock 1.12.1.1

Thank you, and sorry for interrupt you

Quote from Roman

https://support.aternos.org/hc…nable-to-connect-to-world

Thanks for your help, it's really useful, but one of my friend still can't join, even with vpn, do you know how to fix that? Please