Same issue here. Dell XPS 18 that was recently purchased and still covered under return policy, thankfully. Noticed issued around the same time as I upgraded to Windows 8.1 but that could be a coincidence. Been talking with Costco and Dell tech support and no identified solution to date. No signal issue (always shows 'Excellent') but have noticed better quality signal when sitting 10 feet from WIFI router. Connection still drops (no actual change in signal quality or other) intermittently and the PC is becoming unusable.
On Intel site, I was prompted to update driver bu the update looks to have been removed. Should we expect a new update soon? Love the PC other than this issue. Is there a dedicated Intel support line for this issue?