Comment 2 for bug 1636395

I can confirm this problem. Since updating to 16.10 DNS fails when openvpn connection is enabled in NetworkManager. Intranet DNS lookups do not work - so the corporate servers cannot be reached. Additionally all my traffic is routed through the VPN and all external internet traffic is blocked.

A partial fix is to disable dnsmasq in /etc/NetworkManager/NetworkManager.conf

[main]
plugins=ifupdown,keyfile,ofono
#dns=dnsmasq

[ifupdown]
managed=false

And to restart NM with: sudo service network-manager restart

After this external traffic works again - but intranet hosts are still not resolvable - so I have to add manual settings in /etc/hosts for the intranet.

In 16.04 openvpn with pushed DNS worked perfectly - the openvpn server has not been changed and is still working fine for other clients.