Apple TV Error 3253

There are nights when a movie downloads fine and I can watch it immediately after purchase, while I am downloading. Other times, the download is painfully slow and need to wait hours before I watch it. And lastly, on other night, I get very slow download speed paired with error 3253 and can't finish a download. I do not think this is an internet problem because the internet on my computer works fine. Also, I can do the network test on the ATV when experiencing the problem. Please help! At this point, I refuse to rent movies off of ATV because it has been very unreliable.