In this article I will show you how to make your wireless connection work on Broadcam BCM4311 network interface card, on Ubuntu, Debian and Linux Mint Systems.
To fix your wireless problem, this is what you have to do:
Remove the default driver:
$ sudo apt-get remove --purge bcmwl-kernel-source
Install a the Linux Firmware nonfree drivers:
$ sudo apt-get install linux-firmware-nonfree
Load the b43 module:
$ sudo modprobe b43
To make it work automatically, do (thank you Ja7i3r for this hint) :
$ sudo su
# echo "b43" >> /etc/modules