I've been having this problem for a while. I used a Wi-Fi repeater/extender but it drops intermittently and I just got sick of it eventually.
Are all Wii U's like this? I have my Wii right beside it (Its fully off, so I know theres no interferance) and I can easily watch netflix all day without it dropping. Without my Wi-Fi extender I'm lucky if the Wii U even get on netflix, assuming the extender doesn't drop me mid view. All my other devices work fine at the location where I put my Wii U.
I'm starting to think if I should take it to Nintendo to address the issue. Does anyone feel like the Wii U's wifi reciever just sucks, or is it just me?