iTunes doesn't find Airtunes when connected with cable, only WiFi

[Geir2]

I have an Apple TV with Airtunes enabled. But apparantly, it's not possible to connect to it from PC's who are connected to LAN with cable instead of WiFI? Does anyone know why?

More details:

I have 3 PC's:

PC 1: , Windows 7 64-bit with iTunes 9.1.1.12 (latest)
Stationary, connected to LAN using cable in a Gigabit switch

PC 2: 100% fresh install of Windows 7 32-bit and iTunes 9.1.1.12
Stationary, connected to LAN using cable in a Gigabit switch

PC 3: Win 7 32-bit with iTunes 9.1.1.12
Netbook - connected through WiFi

Apple TV device (latest firmware) is connected to same LAN using cable as well. All PC's can ping the Apple TV without problems.

So the problem is that iTunes doesn't find the Airtunes device (the output dropdown selector doesn't show up). I first tried on my main PC (PC1). It didn't work, so i tested on PC2 (wich is a fresh install of both OS and iTunes!), but same problem there.

But then the weird thing happened. I tried to install on my netbook, and it worked! Only difference is that the netbook was connected through WiFi. I don't see why that would matter, but just for fun i tested to disconnect WiFi, and connect with cable and boom - airtunes selection dissappeared! As soon as I disconnected the cable and reconnected WiFi, it appeared again.

Why on earth would Airtunes only work on WiFi? As you can see on the attached screenshot, network configuration is equal on Wifi and cabled connection.

 

[GGJstudios]

AirTunes is exactly what its name implies: a wireless (air) connection, and it only works with an AirPort Express. It doesn't work via cable.

http://www.apple.com/itunes/itunes-news/2010/02/itunes-and-airtunes.html

 

[Geir2]

AirTunes is exactly what its name implies: a wireless (air) connection, and it only works with an AirPort Express. It doesn't work via cable.

You are wrong on both statements...

 

[GGJstudios]

You are wrong on both statements...

You're the one asking the question. Prove otherwise.

iTunes: About AirTunes

Edit: I see that with Apple TV Software 2.3 and later, you can now stream music from your Apple TV to other AirTunes speakers. However, it's still wireless streaming.

 

[Geir2]

You're the one asking the question. Prove otherwise.

Apple TV has the Airtunes service, so I don't need an Airport Express (as mentioned in my post, it works fine when connected to LAN via Wifi). Regarding cable:

I just tested iTunes in OS X from a virtual machine in Win7 on PC1 (cabled) and it works fine. But not from the host, even though they share the exact same physical network connection!

I think it's a bug in the latest Windows version of iTunes, cause there's others with a similar problem.

Note: I don't have any firewall or security software on two of the PC's i tested with.