Slow or no wifi fix for Ubuntu 12.04

After upgrading to Ubuntu 12.04, my wifi stopped working, ie network manager was showing my laptop as connected to my home wifi network but I couldn't connect to internet for some reason, ping and DNS resolving didn't work neither apparently.
After looking around I found something useful that I had to tweak for my system to get it work, so simply taking their solution 2 and tweaking it to look like :

sudo rmmod -f iwlwifi
sudo modprobe iwlwifi 11n_disable=1

If you notice that the wifi speed improved, then make the change permanent :

gksudo gedit /etc/modprobe.d/iwlwifi-disable11n.conf

and add this line to the file:

options iwlwifi 11n_disable=1

save and quit.

If you're on battery, turning off power management could help as well

sudo iwconfig wlan0 power off