I never cared too much about the "preferred" wireless access point because I only ever had one. However, recently I've moved my Wii U to elsewhere in my house and hooked it up to a computer monitor. Following this, Splatoon (virtually the only game I ever use it for) drops its internet connection MUCH more frequently, not always but much more than prior to the move. I'm attempting to solve this by adding a new access point with fewer obstructions between it and the console.
Because the old secondhand router I picked up turned out to be incapable of wireless (manufactured when Windows XP was the hot new thing), I set up an old MacBook I had to do internet sharing. It's too much trouble to do this every time I want to play the Wii U, so I connected to that access point, set it as preferred, and left the existing connection in place, hoping that the machine would fall back to it when it couldn't access the Macbook.
Instead, not having the Macbook set up leads to the console reporting that it could not find an access point, even though one that was set up was in range, just not preferred. It seems that it will only connect to an access point that is set up as preferred.
I found one person on Google who had this problem, had posted in Nintendo's support forums over a year ago and never got a reply.
Is this intended behavior? Is it possible to fix?