Homesharing on iMac has to be on same LAN Segment?

I have an iMac running IOS 10.8.3 and iTunes 11.0.2. In my family room is an Apple TV 1 and in my home theatre room is an ATV3. Do they all need to be on the same LAN segment in order to enable Homesharing ir can they be connected through a local switches?

Here's the connection scheme:

iMac --> 16 PORT Switch --> 4 PORT Switch --> ATV3 (not working)

iMac --> 16 PORT Switch --> ATV1 (working)

The ATV1 seems to be ok although it's a bit flaky when streaming (diff problem)

The ATV3 was working fine when connected through one switch to the iMac but now that there are two devices in between, it does not see my IMac Homesharing.

IS an alternative solution to connect them all through the same SSID in wireless?