When i join the server with public ip, i crash

hi everyone, i tried to make a server with sponge, it work!
but if i join the server or a friend join, with public id (not ipv4), i crash and server say “connection lost” or “connection timed out”, i have: ryzen 5 2600, rx 580 and 16 gb ram, i give to the server 3/4 gb.
can someone tell me why my server dont work?
(if i join with private ip (ipv4) it work…)
ps: sorry for my english i’m italian.

public id (not ipv4)

What exactly does this mean… At the end of the day all Minecraft server communication happens over IPv6/IPv4…

Can you share a pastebin or gist of the server log file when this happens?

hello, thanks for replying, I said to you, to enter “remotely” I use my ipv4 and add: 25565, instead to access my friends on the myip.is website and I give him the one followed by: 25565.