Thx for this URL... i had actually seen this before. That's where I got the (potential) indications on:
Port 3689 - Digital Audio Access Protocol (DAAP), iTunes Music Sharing, AirPlay
Port 5009 - (Unregistered Use), AirPort Admin Utility, AirPort Express Assistant
Port 5353 - Multicast DNS (MDNS), Bonjour, AirPlay, Home Sharing, Printer Discovery, Back to My Mac
> Has anyone encountered this issue before with wireless routers blocking Mac Mini <=> Airport Express streaming audio function ?
> Are these the correct, or only, ports involved in both the Airport Utility discovery function (for wireless apple devices) and the iTunes Remote Speaker audio streaming function ?
The fact that Airport Utility can no longer see the
Airport Express means that it has nothing to do with
ports but with fundamental connectivity. Does the
router for the existing wireless network recognize
the Airport Express and is it configured to create
an extended network? What is the device that
controls the existing network?
What you have at this point is a wireless network
configuration issue it seems, since the existing
network is "removing" the Airport Express node.
Here's some more info I learned when dealing with Apple Tech Support.
The Airport Utility app on my Mac Mini can see the Airport Express when I perform a hard reset (on the Airport Express). At that point I walk through Apple's process to configure the Airport Express for wireless audio streaming. I join it to the same existing wireless network that the Mac Mini is already attached to. Once the Airport Express configuration is complete and it automatically reboots to join my Home wireless network, the Airport Utility on my Mac Mini can no longer see it. Meanwhile I can validate that my wireless router has indeed allocated an IP to the Airport Express and shows it as an attached device.
As a side note: I took this Airport Expresas and a Macbook Pro I have to my local Genius Bar where they successfully joined both devices to the store's Apple network and streamed music to the airport Express. This seems to at least indicate that I don't likely have a hardware issue with the Airpor Express.
It was the opinion of both the Genius Bar tech and the Airport Express specialist I called from Apple Support that it was likely a blocked port issue... thus my pursuit of this approach to troubleshooting why I can no longer stream music to this Airport Express.
Hazzah ! Issue resolved.
Router is a Netgear WNDR4500 and within its basic router setting for the wireless networks is
a selection called 'Wireless Isolation'.
With this enabled, attached devices can only see the Internet, not other devices on the LAN.
While this is a arguable security approach, disabling it allows Mac Mini - Airport Utility to instantly see Airport Express and iTunes now has a remote speaker selection (as does PandoraJam) !
Thank you to those who offered advice... much appreciated.