How to use AirPlay on a 802.1x network

I'm trying to connect an AppleTV 3 to an 802.1x network, but I failed to use Airplay: no Airplay buttons appear on proper apps on my iPad 2. Only if I join a commercial ADSL network, anything works well, but this solution is not applicable to my aims (using Keynote from iPads to our interactive whiteboards).

May I install a profile configuration (link) to my AppleTV? This would solve all my problems... I tried, unsuccesully 😟.

You can find a description of the network I tried to join here (in Italian).

I don't need to play any movie downloaded from iTunes, so I shouldn't need any Internet connection, should I? The captive portal described in the link above in necessary only for Internet, not to join the internal network.

I'm available for any further explanation and I hope to have been clear...😀

Filippo