I've been having the same problem with my Vaio EB. I actually returned my first laptop because
Sony couldn't figure out what was wrong. When my second brand new laptop had the exact same problem, I looked this up. People with all different computers are having this same problem.
I installed the 13.1.1.1 driver earlier, and I thought I solved the problem, because my wifi stayed on for about 4 hours without fail. Then I shut down for a while and turned it back on later, and the wifi went off.
I just downloaded the 13.2.1.5 driver. Does this actually work? I can't deal with this problem forever. I will go insane.