Is your WiFi connection working slow after doing an upgrade to Ubuntu 11.10 Oneiric Ocelot? This may be caused by your Atheros modules. In this tip we will show you a solution that may help you restore the default speed of your WiFi connection. This solution is also workable for LinuxMint11.
Open the terminal and run this sequence of commands:
gksu gedit /etc/modprobe.d/ath9k.conf
And at the end of the file, insert this line:
options ath9k nohwcrypt=1
Save your file and exit. Reboot now your system, then test again your WiFi connection to see if its speed is resolved or not.