alt Hacker NewsIroh or n0 seems to solve that. It's they're underlying network protocol. When you're behind some cgnat, iroh falls back to public iroh relays hosted by n0: https://docs.iroh.computer/concepts/relays#public-relays
However you could self host one of these on a public server you own. Then you're independent.
Seems like nothing can really get around this without a server/relay/TUN/STUN server. Peer to Peer messaging just doesn't work otherwise.
Saw Iroh post on HN. Just wonder how it differ from Nostr, Scuttlebutt or Yggdrasil or DHT etc? Many from Nostr claim that they are successor of scuttlebutt, but many devs from Scuttlebutt highly dispute that.
Be good to get a comparison between these protocols for devs who want to use them.