I've tried a few combinations: ATV gen 2 connected to wifi- works great. Plugged in the ethernet cable disabling wifi- works great. Swapped the gen 2 with the gen 4 without ethernet cable and connected to wifi. Connects to wifi and receives ip address, but when I go to the app store nothing loads. When I check my network settings I no longer have an ip address but still connected to my wifi router with a strong signal. Plug in the ethernet cable disabling the wifi, I get a stable ip address (doesn't disappear), but all the itunes apps (app store, movies, tv, music) take about 20 minutes to register that it has internet access. When it seems I'm connected I get a lot of blank/white tiles instead of pictures or movie covers. Opening apps like YouTube and Hulu I get an endless spinning circle with a blank screen. After a couple of restarts, about 20 minutes of letting it sit, and loads of patients, I can eventually watch a movie or get into Hulu and get a show going.
Thinking there must be some sort of interference with my entertainment center causing the connection issue (like the metal on the dvd player and other devices), I swapped the gen 4 with a different gen 2 at a different TV in another area of the house with a simpler wooden TV stand. The results were the same. Connects to wifi with a strong signal, but doesn't keep the ip address long enough to use it.
I spent three hours swapping ATVs around last night and could not get the gen 4 to actually streem anything or run downloaded apps. I ran network tests on the gen 2's and they were successful. I rebooted twice this evening and was able to get Hulu playing, but not everything is loading in the itunes apps. I haven't tried taking it to someone elses house yet. I might try that this weekend, and it may work fine like it did at the service office. I don't know to what extent the service office tested it other than getting a movie and a YouTube video to play. Could there be something I need to do to my wifi router to let the two speak to each other better? Or could it be a faulty network card?