It was suggested to me to try and use 0.0.0.0 localhost in my /etc/hosts file, bu that's not doing anything.
With netstat I'm seeing that both jack-dssi-host and WhySynth_gtk are opening ports, but the GUI still doesn't open up.
[sean@localhost ~]$ jack-dssi-host whysynth.so
jack-dssi-host: Warning: DSSI path not set
jack-dssi-host: Defaulting to "/usr/local/lib64/dssi:/usr/lib64/dssi:/usr/local/lib/dssi:/usr/lib/dssi:/home/sean/.dssi"
jack-dssi-host: OSC URL is:
osc.udp://localhost:19884/dssi/whysynth/WhySynth/chan00
host: Ready
WhySynth_gtk starting (pid 22764)...
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and this from netstat....
udp 0 0 *:19884 *:* 22757/jack-dssi-hos
udp 0 0 *:19885 *:* 22764/WhySynth_gtk
Sean