Você precisa instalar o bcmwl-kernel-source
e usar o driver do kernel wl
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Abra um Terminal e instale o pacote bcmwl-kernel-source:
sudo apt-get update
sudo apt-get --reinstall install bcmwl-kernel-source
Carregar driver
sudo modprobe -r b43 ssb wl brcmfmac brcmsmac bcma
sudo modprobe wl
Outra maneira de instalar o bcmwl-kernel-source
de aqui
adicione repo e instale
sudo add-apt-repository ppa:longsleep/bcmwl
sudo apt-get update
sudo apt-get install bcmwl-kernel-source
compilar
sudo apt-get install git-buildpackage
mkdir bcmwl-ubuntu
cd bcmwl-ubuntu
git clone https://github.com/longsleep/bcmwl-ubuntu.git bcmwl-ubuntu-master
cd bcmwl-ubuntu-master
gbp buildpackage -b -uc -us
ls ../*.deb
../bcmwl-kernel-source_6.30.223.271+bdcom-1longsleep0_amd64.deb
sudo dpkg -i ../bcmwl-kernel-source_6.30.223.271+bdcom-1longsleep0_amd64.deb