I had an issue that sounds like this, after disconnecting from an OpenVPN session my DNS would fail, killing dnsmasq and restarting network manager would resolve the problem.
To fix it I removed all network interfaces (lan/wifi/vpn etc) from network manager, rebooted, then re-added the interfaces, the problem appears to have gone away. Hopefully others find this helpful.
I had an issue that sounds like this, after disconnecting from an OpenVPN session my DNS would fail, killing dnsmasq and restarting network manager would resolve the problem.
To fix it I removed all network interfaces (lan/wifi/vpn etc) from network manager, rebooted, then re-added the interfaces, the problem appears to have gone away. Hopefully others find this helpful.