I have had the same problem for a while. I have 1st gen ATV. I also have atvFlash but even after a factory restore of the atv, with nothing running, itunes won't 'see' my atv. I have tried:
restarting my pc, router (2wire), and atv. Tried shutting off my router firewall and windows firewall.
downgrading to itunes 9.1.1.12
unsyching
reinstalled atvflash as well after all this
switched ethernet cables (i have had nothing but trouble with my wireless - it kept resetting or losing it's connection though I have since tried to get things going with that to no avail)
hooked it directly to my computer via the ethernet
run atv diagnostics - everything checked out fine
with atv flash i am still able to stream to nitotv and xbmc
last night i was able to use itunes (i am able to log in on my atv) to watch a movie, am able to watch trailers
Probably tried other things but am just at a loss for whats going on. Have seen some issues with 2wire routers but you search for anything and something will come up. My PS3 and Wii both work fine on the network, the wii is on wireless - no issues streaming.
I can't even get the box to enter in the 5 digit from atv into itunes. I had previously been running things and synching fine, all media types. My itunes until i restored it yesterday, had the music previously synched but would not update running...and now its down to nothing.
Able to FTP from PC to ATV with no problem as well...
No multiple speaker icon available (used to be and worked fine)
Searched at end for suggestions/ideas but am trying all and getting no results.
Any ideas?
Any suggestions