I don't know if this can be helpful but I have no problem with Apple TV (ATV3). Though this is with a RB2011UiAS-2HnD and I'm using bridge mode.

Hello, I'm quite new to RouterOs but with all the information available on the web I managed to get my RB2011 up and running. Even though it's still impossible to get port forwarding working. Of course I have read about this topic and I have found many examples. I believe I'm trying accoording "...