After the full update of Ubuntu 16.04 we noticed an unpleasant error – the DNS leak protection in Network Manager stopped working.
Watch the video with a demonstration of the error and its elimination.
To fix this bug, you need to install the following Ubuntu packages openresolv nscd unbound, by running the command:
sudo apt-get install openresolv nscd unbound
Then reboot your VPN network and no more DNS leak!