This did not work for me and my 15" Macbook Pro 2013.
I had a bad ethernet cord, so solving this took 10x as long.
Running the Updates in AppCenter seems to be working. Click on the Broadcom Driver. Yes it worked after reboot.
I have WiFi icon showing. Get Wired Connection and Run the Updates FIRST.
Then install the bcmwl-kernel-source Drivers (you have ...