After installing or upgrading to Ubuntu 11.04 or 11.10 Oneiric Ocelot you noticed that the connexion is too slow when using the wifi, this is a simple solution. This solution works also for LinuxMint.
1- First method : You need to disactivate IPv6, to do that, open terminal and enter the following commands:
echo "#disable ipv6" | sudo tee -a /etc/sysctl.conf
echo "net.ipv6.conf.all.disable_ipv6 = 1" | sudo tee -a /etc/sysctl.conf
echo "net.ipv6.conf.default.disable_ipv6 = 1" | sudo tee -a /etc/sysctl.conf
echo "net.ipv6.conf.lo.disable_ipv6 = 1" | sudo tee -a /etc/sysctl.conf
Then restart your system.
If you still have the issue, follow also instructions on step 2.
2- Second method : A second solution for this issue can be by using the following :
Open terminal and enter the following command:
gksu gedit /etc/modprobe.d/ath9k.conf
at the end of the file add this:
options ath9k nohwcrypt=1
Save an restart your OS.