My wifi stops working randomly till I reboot my laptop.
I dont know if this helps :
lspci -nn | grep 0280 04:00.0 Network controller : Ralink corp. RT3290 Wireless 802.11n 1T/1R PCIe [1814:3290]
6 years old problem...
It's been reported multiple times and the ubuntu developers couldn't care less.
Having the exact same problem since forever and I doubt I'll live to see the day it gets fixed.
Your wireless whatever doesn't matter, it happens on everything (realtek, intel, atheros etc)
Only "workaround" I could find so far was to remove and reload the modules. It's beyond pathetic.