What a nice surprise to see that after a fresh setup of Ubuntu 12.04, you can’t use Internet connection !
That’s really weird, and in the same time strange because I only have this issue with one Access Point.
I can connect to the Wireless Network, but after 5 seconds I can see that I lost 30% of packets and can not use Internet connection.
To see which driver you are runnning, please use this command :
my1@nano:~$ sudo lshw -class network *-network description: Wireless interface product: AR9285 Wireless Network Adapter (PCI-Express) vendor: Atheros Communications Inc. (...)
After investigation, I found a solution to fix this issue :
sudo rmmod ath9k sudo modprobe ath9k nohwcrypt=1 echo "options ath9k nohwcrypt=1">>/etc/modprobe.d/ath9k.conf
Try now to connect to your Wifi, and that should be better.