I am NOT a compute person. But I bought a new ASUS laptop running 8.1 and it would not connect to public wifi, and would to my home network. After trying to solve it for 4 months I gave up and figured I was the problem. But recently I've needed to take it out and about again and spent 6 hours online yesterday scrolling through every old thread everywhere. Here is what I found and it did work for me as I am now sitting at Chic Fil A and have wifi! Control Panel> Network and Internet> Network and Sharing Center> Change adapter Settings> Wifi> Organize> Properties> Configure> Power Management> Uncheck: Allow the computer to turn this device off to save power.
I don't know why it worked, but it is the only thing I changed.