Same problem here on an Acer E1-571. Bought it half a year ago with Windows 8. 'Upgraded' it a couple of weeks ago to 8.1 via the Windows shop (for free - thank you Microsoft :-( ) . Now I find myself toggling the wifi connection at each wake-up. All other devices on the same network keep on running smooth (another Windows laptop, a puppy Linux desktop and two Android phones).
Been asking Acer support to help. Poor guys are running in circles: Did you upgrade the wifi driver? Tried the 'Vonnie solved'? Are you on the latest version of your bios? ...
Can't understand big companies just keep you hanging on (does that sounds like Kim Wild?). Maybe I missed the correct reply in the chain. But some engineer might answer something like: 'We are working on it. Hope to solve it in a couple of days.' or 'We still believe it is your network not functionning.' ... .
Cheers