After using Win10 for over a month I have experienced issues with the WiFi drivers occasionally not being loaded when waking from sleep mode.
This only started happening when I set the WiFi to turn off when asleep to save battery power.
I reset the option about 10days ago and have not had the issue since.
If you are having problem with WiFi dropping on wake up then try...
All Settings>System>Power & Sleep>WiFi (When on battery, stay connected to WiFi while asleep)