jmcalafactor - I had a similar issue you described on this forum thread. I installed this card into my desktop with a mini pcie to pcie adapter. It worked great for couple of days using the wireless AC with no problems. Windows 8.1 was reporting 600+mbps until today. The wireless card is acquiring a valid LAN IP but it won't route "LIMITED ACCESS" for some reason. I tried uninstalling and reinstalling the driver without any luck. I have not moved my pc, moved the router or modified any configuration on my router. I even tried modifying the advanced wireless nic setting with no luck.
Preferred Band: 2.4 and 5.2ghz
Wireless Mode: Tried each option.
The generic response by intel "The 5 GHz band is usually more susceptible to walls and obstacles. " doesn't apply here. My other AC enabled devices works fine next to the machine i have issues with.
My macbook pro sitting right next to me as i type is working just fine.
Hope Intel can work their magic by providing a driver that resolves these issues.