I've just bought a new rMBP 15 inch a few days ago and for some reason every time it goes into sleep / powernap mode, when I turn it back on the wifi doesn't work. The odd part is the wifi still appears to be connected but I can't transfer any data, go online etc. I have to turn wifi off and on in order to get back online.
Any ideas what's going on? I have Mavericks installed and completely up to date.