Another xps 15 killer WLAN (now Intel) WiFi problem

Hi,

So i bought my xps 15 (9550) a year or so ago and my wifi was always patchy but recently when I booted I had the dreaded red x and no amount of rebooting, flushing, disabling/reenabling, etc. did anything to help.

I figured I may as well bite the bullet and replaced the card so bought the Intel 8260 but despite having used the killer uninstaller and seemingly having installed the Intel driver correctly, nothing has changed. I've re-run all the dns flushing type stuff but nothing worked.

Any ideas what to try next? Only thing to mention is that I have one unknown device in device manager which I presume is part of the problem.

Any help much appreciated, thanks.

Mark