Unable to use Wifi on Lenovo Z5070
From here https://bugzilla.kernel.org/show_bug.cgi?id=83641#c1
"There is a new version of this driver at GitHub. You will need to have the package with the kernel headers installed.
git clone http://github.com/lwfinger/rtlwifi_new.git
cd rtlwifi_new
make
sudo make install
This version of the driver will be submitted for inclusion in kernel 3.18. I ran it for 39 hours with no disconnects."
this solution works for me. I hope that help
Note
If You update the ubuntu, and this update has ubuntu base updates, so you need to run the following again.
make
sudo make install