norovid on Nostr: Most of the relay set ups tutorials that I find, imply to rent a VPS and and a static ...

Most of the relay set ups tutorials that I find, imply to rent a VPS and and a static IP where to point the relays.
I'm an ignorant but I don't understand how I can download torrents, via upnp without sharing my IP, but I have to publish my IP.
Am I missing something here? Couldn't be a better way?