Here’s a scratchpad on how Jacktrip Hub Mode does audio routing as of early September 2020.

Starting the server in Hub Mode (capital-S instead of lower-case S) with the “-p” option offers four ways to configure the server.  Here’s an example launch string that would fire up a server in Mode 2:

jacktrip -S -p2

Mode – 0 (the default – my machine hears everybody and everybody hears the mix that I send them)

Mode – 1 (loopback – everybody hears themselves but nobody else)

Mode – 2 (everybody hears each other, but not themselves)

Mode – 3 (reserved for some whacky stuff with Supercollider and auto-generated internal IP addresses — looks OK in the routing, but scroll down check out what shows up in the terminal)

Here’s the whacked stuff that shows up in the terminal…

Mode – 4 (everybody hears each other and themselves)