I just came back from troubleshooting a PPX with WiFi connection issues from a fellow backer in my hometown. I took my fully working PPX with me and first he showed me his, where the unit would see the networks, connect to the one he had set (and also reset when I was there), only to not get any IP address and the WiFi to turn itself off completely. Each time we went back into the WiFi settings and turned the WiFi on, it would try to connect and then just turn the WiFi off by itself. Not even connecting to a hotspot would work.
So I took mine out of the bag and proceeded to connect it to the same WiFi network as he had tried. Lo and behold, my PPX did exactly the same as his! 
I could not get it to connect to anything, not even my iPhone’s hotspot, the WiFi would just crash.
So we had successfully reproduced his issue on my unit which has worked perfectly fine so far at my home.
I then realized that the flat he lived in was bursting with WiFi networks. My laptop and iPhone were picking up at least 16, sometimes different than that even. I believe that the sheer amount of WiFi networks is causing something to overflow and crash the WiFi stack.
Good news is that I’ve managed to reproduce the issue, and got a log file of the unit while in that environment. So now the engineers may finally be able to discover what’s going on once I send in my findings.
For those that reported this issue here: how many networks do you see in your phone / laptop / PPX?