Peers _always_ connected directly to transfer files

A third party server kept an index and provided search, it did not forward traffic between peers

https://docs.iroh.computer/concepts/nat-traversal.md

"If NAT traversal fails, iroh automtically falls back to routing traffic through the relay server"

It has not "solved" the hole punching problem any better than anyone in the past

Alas, it does worse than predecessors by adding a non-P2P default (cf. option)