Strange thing I discovered today. A family member of mine got a new external HDD to expand the storage of their Wii U. After plugging it in and configuring it correctly, they later discovered that the console would no longer connect to WiFi. Curious, we experimented by powering down the console, turning off the drive, then powering it back on. Sure enough, the console connected to WiFi without issue. A bit of googling lead me to this page, which explained the problem. Apparently the HDD in an enclosure created enough electromagnetic interference that it conflicted with the wireless bands used for wireless internet. The solution: move the drive 1 foot away from the console. I couldn’t help but laugh that this worked, though it makes sense. The range of interference is rather small, and since the USB cable for the drive wasn’t overly restricted, increasing the distance between it and the Wii U was sufficient to avoid the problem.