I am afraid I can't help as I don't have a Wii U yet. But if no router will work then how is everyone else getting on the eShop? I think you heard wrong there. It might be your NAT settings. A few years ago I was having problems on Xbox Live where I could barely get onto the marketplace and not connect to some friends. It turned out my NAT settings where set to strict. I simply had to change it to open. Am sorry but I can't remember how I changed them now as it was a few years ago.

maybe i need to change the router channel.

is this router good for wii u http://www.amazon.com/Medialink-Wireless-Router-802-11n-Inter...

Definately sounds router related, although as posted here and elsewhere, wired lan is actually slower than wifi on wii u due to nintendo skimping on usb however at least you should have a stable connection.

If I where you I would go for someone like Netgear or D-Link. However it is most likely just a simple setting that needs changing on your router. Have your tried putting your Wii U as a DMZ.

What is DMZ

This is the guide I followed a few years ago. I know it says Xbox but its all the same.

http://news.softpedia.com/news/Guide-to-Opening-NAT-Xbox-360-...

Ya, this isn't even close to Nintendo's fault. Your Wii U will connect to any router that is able to support it. Wired LAN is actually worse in some cases. I can top out at a slower than wireless connection speed, or just make it a problem/clutter w/ wires. Usually your internet company will have a recommended router for purchase using their service, and even then, you need to upgrade the firmware now and then. Updating my router has usually been the problem when connection is crappy on game consoles(Nintendo mainly, Xbox, (especially) Sony have more leway when connecting their console to internet). There should never be a time, where you need to mess with settings on your router besides wireless security or ability to do wireless in the first place.