Using a USB hub with Wii U
A USB hub can be used with the Wii U console in order to expand its available USB ports. This is to support the GameCube Controller Adapter for Wii U, which needs two free USB ports in order to fully connect to the system.
Nintendo recommends using a self-powered USB hub, i.e. a hub that uses an external power supply instead of drawing power through USB. Devices that draw their power from USB ports are known as "bus-powered" devices, and are not recommended for use with Wii U.
A USB hub needs to supply over 500mA per port in order for the GameCube Controller Adapter for Wii U to function properly.
Please refer to the diagram below when connecting a USB hub to your Wii U console.