For several OS X versions now, I've had the same issue on two different laptops - a macbook air and a retina macbook pro. Every night I put my laptop to sleep. About 50% of the time, when I wake to use it the next morning, the wifi does not work. If I click on the wifi icon and let it scan for about five minutes it will eventually find my network and I have to manually select it. Otherwise, I have to reboot. I've searched and tried different solutions and nothing seems to work. I dread taking my laptop to apple because they will likely be unable to simulate the issue since it usually takes some time in sleep mode before the wifi is lost. Does anyone have any suggestions? I can't remember everything I've done over the past 18 months, but I'm certainly not going to format/reinstall the OS once again. Thanks.