Hey, glad your brother is OK.
The problem with Wifi apart from the initial setup is that it's much less reliable (for audio streaming) than a wired network. I guess I was worried that people might end up evaluating their Wifi network instead of the unit and/or consume pages trying to sort it out.
[Edit] (And there, I am assuming that it's been set up to stream audio over the network, which is not the case if you plug in a USB stick.)
Plus, I had already plugged it all together with a RPi 2 (which doesn't have onboard Wifi)
Most USB Wifi dongles will/should work if you want to try it. Just be aware that if you get dropouts, the first place you want to start looking is your network channel/interference from neighbours etc.