I experienced the problems described where I lost DNS resolution when connected to a corporate VPN.
With help from a coworker I fixed it temporarily by commenting
#dns=dnsmasq
in /etc/NetworkManager/NetworkManager.conf as recommended in bug #903854
P.S.
I lost a lot of time trying to figure out why my VPN connections were suddenly no longer working.
I hope Ubuntu finds a permanent solution that keeps private VPNs working.
I experienced the problems described where I lost DNS resolution when connected to a corporate VPN.
With help from a coworker I fixed it temporarily by commenting ager/NetworkMan ager.conf as recommended in bug #903854
#dns=dnsmasq
in /etc/NetworkMan
P.S.
I lost a lot of time trying to figure out why my VPN connections were suddenly no longer working.
I hope Ubuntu finds a permanent solution that keeps private VPNs working.