Airplay device not showing up in list

Problem: I have an airplay device (Bose soundtouch) and this device is not showing in the airplay list in iTunes on a mac (macbook , imac)

Setup:

I have a switch (netgear). This is the main switch in my network. The mac is connected to this switch using an ethernet cable.

I have a wireless router (Belkin N600) that is set to "Access Point mode". The wireless router is connected to the main switch with a ethernet cable.

The Bose SoundTouch is connected to the wirless router through wifi (the router itself also has networkports).

Noticed Behaviour:

Bose has it own application. This application has always access to the the device no matter how the client is connected to the device.

If the mac computer is connected to the main switch , iTunes on this mac will not detect the SoundTouch as an airplay device. However if I connect the mac directly to the wireless router (via wifi) the itunes will detect the Airplay device.

Can someone explain why this is is an how I can resolve this. As the wireless router is in "access point" mode all firewall/routing functionality is disabled.

I noticed this behavour in the latest iTune (11.1.3) en the previous version.