Thanks, so this one works for my Mac (.50) in particular but not my RPi on the same network with an SSH server, because turns out it doesn't advertise that by default.

"you can’t ask dns-sd to just dump all the advertised mDNS services on your network": I ran into this too. So besides the defaults and maybe network itself standing in the way, the tooling around mDNS is user-unfriendly.