Yeah, also the two sides can exchange (encrypted) notes about their apparent network environment (including their public IP address, as reported by the rendezvo

Yeah, also the two sides can exchange (encrypted) notes about their apparent network environment (including their public IP address, as reported by the rendezvous server), which might give them a clue that they're on the same LAN. Also see https://github.com/warner/magic-wormhole/issues/48 https://github.com/warner/magic-wormhole/issues/48 for some discussion about making things work when you're connected to each other but not to the internet, e.g. an ad-hoc wifi network. It doesn't work at all now, but it totally should.