I have a problem with my wifi connection. I have a HP 355 G2 and WiFi doesn't work on 14.04, 14.10 or 15.04 and 15.10. I can fix this like this:
sudo add-apt-repository ppa:hanipouspilot/rtlwifi
sudo apt-get update
sudo apt-get install rtlwifi-new-dkms linux-firmware