Okay, bare with me on this one. I had been using an Apple TV 2 successfully for two years streaming content from my 27" iMac. Occasionally the connection would drop, but that was almost always fixed by a restart. A couple of weeks ago I had a major hard drive failure on my iMac and had to start from scratch. In the process, I upgraded from Lion to Mountain Lion. Since then, I have not been able to get Home Sharing on the Apple TV to work. Wasn't sure if this was a matter if just tinkering with settings, or if it might have had something to do with upgrading to Mountain Lion. My setup is this: The 27 inch upstairs in my office. The Apple TV downstairs in the living room. Prior to the crash, everything had been working fine, including connecting to the network with the iPad, our second iMac, and, of course, the Apple TV. Home sharing worked fine. I need to emphasize here that this was all done without a router. Anyways, today I tried bucking down and figuring it out. Unable to do it on my own, I contacted Apple Support. Basically they told me that I needed a router to get Home Sharing to work. What she said was that I could not create a wifi network from my computer and simultaneously use Internet Sharing for the Apple TV. Meaning I need a router to get it working. She was flabbergasted that it had worked previously without a router. She didn't think that was possible. At all. She basically thought I was on crack. So before I go out and buy a router, I thought I'd try this forum. I just don't get it. It seems to me that with the wifi capabilities of the iMac, I shouldn't need a router. And I didn't!!! For the entire time I've had the Apple TV until I installed Mountain Lion!! So I'm stuck, frustrated, and ready to throw our houseful of Apple products out the window. For what it's worth, she advised that I purchase a dual band 2.4 router or an Airport router. One final note: I tried many of the suggested remedies to network problems. Turning Sharing on and off, restarting, deauthorizing and reauthorizing...nothing.