Well, after all this headache I decided not to update my Sony laptop so soon. But soon has passed, and this weekend I finally gathered the courage, time and patience to do it. I was on the safe side, so I made live USB’s of Ubuntu 12.04, Mint 13 and Mint LMDE (Debian based). I tested all of them, and nothing worked. The same weird behaviour happened again… It was able to connect to the wifi but surfing the internet was a torture. After some hours searching forums here and there, I finally found a solution that worked for me. It worked on the three systems I tested, and I finally installed Linux Mint LDME 🙂
So I will post this here as a future reference.
Problem: The computer connects to the internet but the connection is incredibly slow (it might happen on some wifi networks, not all).
Machine: Sony VPCEA46FG (Joao’s laptop is a Sony Z series, but we still have to bring it home to test the solution)
Wifi card: Atheros AR9285
Solution: Deactivate the hardware encryption of the driver. Here’s how:
echo “options ath9k nohwcrypt=1” | sudo tee /etc/modprobe.d/ath9k.conf
sudo modprobe -rfv ath9k
sudo modprobe -v ath9k