Splatoon is out and with it came my first requirement for some stable Internet connectivity from the Wii U.
I was experiencing too many network connection errors while running off of WiFi that I decided to wire it up using trusty Ethernet cables. The only snag in that grand plan is that the Wii U doesn't have an Ethernet Port built-in - you require a USB LAN Adapter.
The only problem is that Nintendo have stopped producing the official LAN Adapters back in March 2015 and they're pretty tricky to find. Thankfully you can use a third-party USB LAN Adapter if it shares the same chipset (AX88772A).
This USB 2.0 to Ethernet Adapter at Maplin is the one I bought and can verify it works.
Avoid the temptation to get their USB 3.0 Gigabit adapter. I bought that one first and it wasn't recognised by the Wii U.