Comment 10 for bug 1671606

I have the similar issue, but I'm using OpenVPN and the symptom is slightly different.

With OpenVPN, the name resolution is normal on the first attempt to connect VPN (after reboot). However, by disconnect and connect VPN again, the name resolution will be broken. As below.

== Reproduce steps ==
1. Reboot system
2. Connect to OpenVPN gateway
3. Issue command "host server.mydomain.com" -> success
   DNS request & response can be seen by sniffing (Wireshark) tun0 interface
4. Disconnect VPN
5. Connect to OpenVPN gateway
6. Issue command "host server.mydomain.com" -> Host server.mydomain.com not found: 5(REFUSED)
   DNS request & response can NOT be seen on tun0 nor ens33 interface

Note A: After step 6, DNS resolution will NOT back to normal unless reboot or "sudo service network-manager restart".

Note B: After step 6, logout and login will NOT make it back to normal.

Note C: After step 6, issue command "host server.mydomain.com 192.168.3.74" -> success, assume 192.168.3.74 is the DNS server behind VPN gateway
DNS request & response can be seen on tun0 interface

== Package information ==
libnma-common 1.2.6-0ubuntu0.16.04.2
libnma0:amd64 1.2.6-0ubuntu0.16.04.2
network-manager 1.2.6-0ubuntu0.16.04.1
network-manager-gnome 1.2.6-0ubuntu0.16.04.2
network-manager-openvpn 1.1.93-1ubuntu1.1
network-manager-openvpn-gnome 1.1.93-1ubuntu1.1
network-manager-pptp 1.1.93-1ubuntu1
network-manager-pptp-gnome 1.1.93-1ubuntu1
resolvconf 1.78ubuntu4

It will became NOT reproducible after downgrading
network-manager 1.2.2-0ubuntu0.16.04.3

OS version:
Ubuntu Desktop 16.04.2 LTS amd64

This test is conducted under virtual machine environment to minimise uncontrollable factors.