ATV3 Has Endless Buffering for non iTunes Movies over Ethernet

I have an Apple TV 3 in my living room. I updated to latest 5.1.1 release. In order to get that update to go through successfully, I had to disconnect from ethernet network and use WiFi. Occassionally, I will run into where I can not stream HD movies that are non iTunes Store files on my iMac. These are Blu Ray rips to MKV, and converted to ATV3 mp4/m4v formats. They play just fine on iTunes via my iMac. I have tried restarting ATV3, iMac, unplugging ATV3 Power/wait, replug.

I have only found 2 solutions that work:

1) RESET the ATV3 and set back up from scratch

OR

2) Unplug Ethernet and use my Airport Extreme WiFi.

What is even more odd is if I try to stream an HD movie that I have downloaded to my iMac from the iTunes store, it plays just fine over ethernet. So I have to think the connectivity via Ethernet is fine. Its very odd considering my ethernet network is completely gigabit. Although my WiFi has full signal and no drops, I prefer to have anything that is stationary like my iMac, Xbox360, PS3, Apple TVs, etc... connected via ethernet. That way my iPhone and iPad do not have any bandwidth competition while I am streaming. Also when I output music throughout the house via iTunes Airplay to my Apple TVs from my iMac they tend to be in better time/sync with one another when all on ethernet network.

My Ethernet network is setup like this:

Office: Cable Modem -> Airport Extreme -> Netgear gigabit Powerline -> electrical outlet in office

Living Room: electrical outlet -> Netgear gigabit Powerline -> Netgear 8 port gigabit switch -> devices (PS3, Xbox360, ATV3, DirectTV, Piorneer Receiver

Bedroom: electrical outlet -> Netgear gigabit Powerline -> Netgear 4 port 10/100 hub -> devices (xbox360 and ATV3)

I have connected my work Windows laptop top the living room ethernet gigabit Netgear switch and did several speed tests. I am getting close to 30mps DL and 5mps UL. I know that is internet speed. But that should give a good indication that local network speed is more than sufficient if that is the sort of internet speed I am getting.

I also ran the network tests on my Xbox360, PS3, and ATV3. All 3 passed. I figured if there was something terribly wrong, one of them would cry wolf.

I scheduled an appointment with Apple tomorrow morning. I think this is a hardware/driver issue with the ethernet or OS/software. They want this to be a per incident support call or to purchase Apple Care. I have Apple Care on everything BUT my Apple TVs. So surely my iMac, iPhone 5, iPhone 4, and iPad 4 agreements will grant me some latitude to allow Apple to take a look into this issue. I only decided to unplug the ethernet and use WiFi as the result of several Google searches for the issue.

Anyone else able to profess this issue? Share anything to help trend the issue?