Investigate why `iperf3-darwin` works while `iperf3` fails with "No route to host" on `macos-15-large`

[AkihiroSuda]

https://github.com/lima-vm/socket_vmnet/pull/83#discussion_r1854780857

/usr/bin/iperf3-darwin seems to be a part of macOS, not a Homebrew formula.

I don't know how iperf3-darwin is built. Can't find any relevant code in https://github.com/apple-open-source/macos . https://github.com/search?q=org%3Aapple-open-source%20iperf3&type=code

[nirs]

Add a question here: https://github.com/esnet/iperf/discussions/1802