Same issue here. I'm certain it's the last update (not that I'm telling anyone here what they don't already know!). I have an ATV 3rd gen, and a 2nd gen. The ATV3 is set for automatic updates; the ATV2 is manual. When I noticed the problem on the ATV3 after the last update (not the one today; the prior one), I checked the ATV2. It worked perfectly fine. Then I did the update, and the same problem occurred. (As you might have guessed, I did all the restore/reset stuff with the ATVs, modem, router, etc.)
And--not that this will come as a shock--today's update made no difference.
In my innocence, I guess I always thought updates were supposed to improve the product, not reduce its functionality. Sigh...