I have random WiFi disconnects on my Kodibuntu box (upgraded to Ubuntu Vivid right now). Sometimes connection lasts for several days, sometimes - for several minutes.
The thing that helped this time is sudo service network-manager restart
.
Sometimes replugging adapter helps. Anyways it happens on all available versions of Ubuntu from 14.04 to 15.04.
During last disconnection I've launched wireless-info script, here is result: http://pastebin.com/Ue610Tht
Will appreciate any idea.
sudo iw reg set RU
helps any as your computer thinks you are in China