Hello, I wonder if I can use the Wii ethernet adapter, or some other kind of adapter so I can connect the Wii U to the internet with an ethernet cable, as I don't have any wireless internet at home.

The LAN adapter? I use it on my Wii U, and it works perfectly fine.

Yeah, maybe it was called that, I don't own one currently, I just wanted to know so I don't get one in vain. Thanks for the reply!

Yep, definitely works.

I can heartily recommend the Wii LAN adapter for Wii U usage. It works like a dream, just stick it in, hook it up, select "Wired Connection" in Network Setup and you're done. Much better and stable than WiFi

I got a cheap third party one off ebay and it works a treat. So very easy to set up and very fast, stable connection.

I've tried this with my wii LAN adapter and while it does work fine, I've ran a few tests and wifi is way faster than the LAN (its the official wii one i'am using, cant speak for 3rd party ones), so your better off to sticking to that if possible.
EDIT: Here's a post i found where somebody else reports the same finding, perhaps its the usb on the lan adapter being v1?!? not sure, but wifi is faster
http://www.gamefaqs.com/boards/631516-wii-u/64768562

I'm finding that WiFi is faster as well, though compared to the person in the link you provided @mozie, I was only getting around 4Mbps on WiFi, and about 1.9Mbps on Wired. My Wii U is less than 2 feet from my router too.

It's also about latency and stability which are both more important to gaming than throughput. I do think there's a bit of a lower connection speed with the LAN adapter but it's only going to be an issue with download speeds and streaming HD media. I did notice that with the LAN adapter I have to stream the videos in the eShop at low quality. If it's a USB 1 device that would explain it and that kinda sucks.

But it does work, is quicker to negotiate, is very responsive and I am yet to have any disconnections. The HTML5 speedtests I have done on it reported <2Mbps despite doing ~8.8Mbps on my laptop. I am yet to test the wireless speed using the same tool so I'm not sure if it's some other problem with the Wii U handling those speedtest sites. TBH I wouldn't recommend going out to get one unless you have problems with WiFi.

edit: oh, and distance from your router won't make any difference at all to the performance of the LAN adapter. Unless you're literally 100s of meters away and are using low quality cabling. It should, in theory, be doing 100Mbps easy.

When my Internet was going pretty dodgy a while back, I could only play Monster Hunter Tri with a LAN adaptor.
With Wifi I would just get constant errors and disconnections, but with a LAN cable I could play without any issues.

Not sure which I'm going to opt with for the long run with the Wii U though, will need more time with the console to figure that out.

Same. About £5 and works fine.

Just tested this again and I'am getting 8.9 mbps over wifi and only 2.2 over the lan connection, havent had any issues either way so ill be sticking with the wifi.

I'm not sure how accurate those tests are because I just reconnected to my WiFi, setting it as the default, and it still only gives me ~1.6Mbps. That said I can now stream the 1080p Hobbit trailer from my NAS with no buffering so it's definitely faster over WiFi.

I'm keeping my ethernet connected but not as the default connection. Hopefully if the WiFi drops out for whatever reason the Wii U will manage to stay online. So that's something I guess. I'm now getting slightly annoyed that it didn't have a Gigabit or even just Fast Ethernet port on the back as a default

true, i would have expected a standard port as a bare minimum, esp considering nintendo's focus on online this time around.

Please god somebody help me!
I have tried various suggestions to get my WiiU online by inputting specific IP addresses etc and this has got me as far as tick for the network device but will not connect to the internet. So I have got myself a USB LAN adapter but when I try to connect it still wont connect to the internet, I have tried manually inputting the IP address etc again but still no luck, it just says that it cannot find the network device.
I know that the adapter and the wired connection is working so that is not the issue.

Has anyone else had this problem and found a way around it?

any advise would be greatly appreciated.
thanks all.....