On my Duo I used to use an N300 USB wifi adaptor (TPLINK TL-WN821N V3 Atheros chipset)
At first it did not work (on an earlier version of VIX, can't remember exactly which one) I found the firmware for the USB adaptor on the net (htc_7010.fw) what I did to get it working was to put the firmware into /lib/firmware rebooted and it worked.

Now on the Quad the same procedure doesn't work any ideas?
I have an old 11g wifi adaptor that works so USB wifi does work on the quad, just bugging me I can't get my fast wifi to work