Friends can't access Minecraft Server on Ubuntu?

Hi. I have a Minecraft server on an Ubuntu server. I and other PCs in my household can already access it, but you can't access it externally (not even with the external / public IP of the router.) And yes, I have already opened the port on the router and on the server. On the server the UFW status is like this:

Can anyone help me further?

At noip.com you can convert your IP address into a domain so that you can also have remote access to the server

Do you have a public IPv4 address at all or does your connection have Dual Stack-Lite? If the latter, then you will not be able to access the server from the outside.

And what do you have now in the answers to your question here

not understood?