I installed Peppermint 4 OS on a very old Sony Vaio VGN-FS742/W. After updating and confirming that all packages, drivers, and firmware were properly installed, Wifi still would not work.
Type of Wireless Connector: PRO/Wireless 2200BG [Calexico2] Network Connection by Intel Corporation
Peppermint was apparently “blocking” my card, or something. I finally got Wifi working by editing 1 file.
sudo gedit /etc/rc.local
rc.local file, add this above the exit 0 line:
rfkill unblock wifi rfkill unblock all sudo modprobe -r acer_wmi