Fritz!Box 7390 International is modem and router (both LAN and WiFI) Apple TV (1st gen, latest firmware) is connected to LAN port on Fritz!Box MacBook Air (newest) is connected to other LAN port on Fritz!Box Fritz!Box also has G/N Wifi network active.
When MacBook and Apple TV are both connected on LAN, iTunes (10, latest version) cannot "see" Apple TV. Apple TV is pingable and reachable using IP-adress or local address appletv.fritz.box. The appletv.local address however does not resolve.
When MacBook is on WiFi and Apple TV is on LAN, MacBook sees Apple TV just fine. It's then also reachable on its appletv.local address.
There's plenty to find about Apple TV not showing in iTunes, but nothing about the LAN/WLAN discrepancy.
What could cause this? Multicasting issues? Any suggestions for a solution?