Ok, so either your firewall blocks everything 😀 or – more likely – avahi and mDNS and zeroconf are all at war 😉
Then I guess you should check out firefly’s log file.
Right after being started, it states various avahi, or mDNS specific stuff.
Also try raising the debuglevel to 5, or 9 before (re-)starting firefly.
Also, what source did you install from, and which package?