The Sputnik version. That indeed reminds me I swapped the wifi card for an Intel one. Because they are better supported and it was cheap.

The original one was definitely working though.

Ooh, can you do that? Broadcom driver drives me up the wall every time I tweak something...

(Apart from that and the HiDPI, the latter of which is the DE devs' fault, the laptop is awesome.)

This fantastic iFixit (Step 10) has all the details you need:

https://www.ifixit.com/Teardown/Dell+XPS+13+Teardown/36157#s...

I was just about to ask what wifi card you had working there. It took me quite a while to get my xps13's broadcom card working with 15.10 and I'm not sure I even remember how I did it. It's putting me off upgrading.