I can confirm, that the Microsoft driver 14.8.8.75 from 2011 is working without any lags, paket loss, high/spike ping, latency problems, disconnects or other problems, and that every single Intel driver, including 15.6.1, is faulty. For example having a lag or complete stop while online gaming every 2-5 minutes. Im on Microsoft driver, and finally after month of problems, everything is working, no lags anymore, nothing. Im glad I found out about this "workaround". Really bad work @ Intel. I still hope they will rewrite the driver and make a stable one in the future.
I had all different kind of problems people wrote about here in this thread, mostly the connectivity getting instable after a time, easily seen by doing a ping and having high latency every few ping. Also noticing when doing online gaming. I was near to replace my card until I found out about the workaround of using the old Microsoft drivers.
It is not the hardware, it is the Intel driver causing the problems. Try the Microsoft one, and everything will work. Deinstall ProSet software, then go into device manager, go to adapter setting, and hit deinstall driver (had to do so 4 times), until it says 14.8.8.75 from 2011 by Microsoft.