Minecraft Server Issues

I have been trying to create a hamachi Minecraft server for a couple of friends and me. Now the server is working but they have a problem when they connect.

They are just floating in the sky, and F3 says they are waiting for chunks to load. After a while, they are forcefully disconnected, so something must be wrong with internet.

I have been looking everywhere for a solution. I have done this in the past for mod packs and older versions of minecraft all the time, and I have never experienced this issue with Minecraft.

We have already made sure, double checked firewall permissions are in order, we are connected and can ping on hamachi server, so I just have no clue what the problem is.