So I was able to install everything correctly, but I don’t know what I’m supposed to do in order for people that don’t have my same IP to see my files. I’d like to share my Jellyfin server with some friends so they can see movies there. I’ve already open the ports, but they can’t still access them, I’m using elementaryOS Hera which is built on Ubuntu 18.04.4 LTS.
You can still use a VPN(Eg. tailscale as recommeded above) to share, since it can bypass the DoubleNAT. You can also setup a proxy(What I’m doing currently), but it requires more setup and also cost a bit(1 - 2 Euros a month).