Airplay on ATV and AX from Lion and ML: ML does not work...

Question

Hi all,
I am having a problem with Airplay under Mountain Lion...but not under Lion.
On a MBP 13 (Summer 2009), I can use iTunes Airplay under Lion to stream music to both an Apple TV and to a Airport Express.  In fact, I can play iTunes music on the MBP, the Apple TV, and the Airport Express simultaneously (all 3 or any 2 or any 1, individually). [Of course, Airplay display mirroring does not work under Lion, but iTunes Airplay does.]
On a MBP 15 (Early 2011), I can use Airplay under Mountain Lion to mirror the MBP's display on the Apple TV and thus through mirroring I can stream the music from iTunes to the Apple TV.  I cannot stream from iTunes to the Airport Express, whether or not I an mirroring to the Apple TV.  In other words, even when the mirroring to the Apple TV mirroring is Off and the Apple TV is off, I still cannot use iTunes to stream music to the Airport Express.  Now the Airport Express speakers shows up as an option in the iTunes Airplay menu, but when I select it in the menu it does not do anything.
In summary, using Lion I can stream iTunes music to both an Apple TV and to an Airport Express speakers, individually or simulaneously.  Using Mountain Lion, I can stream iTunes music to the Apple TV, but only through the use of Airplay display mirroring.  I cannot stream music to the Airport Express speakers even though the AX shows up as an item in the iTunes Airplay menu.
Any ideas how to fix this for ML so that it works as in Lion?  I checked and have the same Preferences set for both the Lion iTunes and ML iTunes.
Thanks,
Switon

Answer 1

...a little more experimentation...
I booted the MBP 15 (Spring 2011) from an external backup of Lion (made immediately prior to switching to ML).  When I turn off the Server Firewall then I can iTunes Airplay to both the Apple TV as well as to the Airport Express.  But when I turn on the Server Firewall, even after allowing ports 3689, 42000-42999 both TCP and UDP, the Airplay does not work.  I could not determine which ports were needed for iTunes Airplay, all I could figure out is that when the Server Firewall is off then iTunes Airplay works but when the Server Firewall is on then iTunes Airplay does not work.  I tried logging all denied packets, but to no avail, I still could not determine which ones were being denied.
Interestingly, when I turn off the Server Firewall and switch on the System Preference Security pane Firewall, I can still iTunes Airplay to both the ATV and AX.  It makes me wonder if when I switched to ML from Lion that some ipfw rules were not left over from the Lion Server Firewall that then keeps ML from allowing iTunes Airplay to work.  (I wonder if I restore my Lion Server, then switch off the Lion Server Firewall, then download and install ML once again, then download and install OS X Server once again, whether the iTunes Airplay would then work?  Maybe when I have some more time I'll try this, in the meantime I'm going to try a little harder to figure out why the Lion Server Firewall stops iTunes Airplay from working.  Dang nabbit, even "ipfw show" does not tell me which packets are being denied when the Server Firewall is ON and iTunes Airplay does not work...does anyone have any suggestions on how to figure out why the Server Firewall is stopping iTunes Airplay from working?)
Thanks,
Switon