WiFi not working on Ubuntu 18.04 LTS Lenovo Legion Y520
Solution 1:
The device is blocked by a platform ideapad driver. Run in a terminal
sudo tee /etc/modprobe.d/blacklist-ideapad.conf <<< "blacklist ideapad_laptop"
and reboot.
And also I recommend to remove the Broadcom driver that you installed.
sudo apt purge bcmwl-kernel-source