Affected me also. To fix it we should download the newer driver that works with 4.15.+ kernels:
wget http://mirrors.kernel.org/ubuntu/pool/restricted/b/bcmwl/bcmwl-kernel-source_6.30.223.271+bdcom-0ubuntu4_amd64.deb
sudo dpkg -i bcmwl-kernel-source_6.30.223.271+bdcom-0ubuntu4_amd64.deb
Affected me also. To fix it we should download the newer driver that works with 4.15.+ kernels:
wget http:// mirrors. kernel. org/ubuntu/ pool/restricted /b/bcmwl/ bcmwl-kernel- source_ 6.30.223. 271+bdcom- 0ubuntu4_ amd64.deb
sudo dpkg -i bcmwl-kernel- source_ 6.30.223. 271+bdcom- 0ubuntu4_ amd64.deb