I am using PPTP VPN connection on Ubuntu 16.04 and it is working fine after fresh boot and when I first establish connection. But if it get disconnected by some reason and I reconnect (it reports it reconnected successfully) it stops working - meaning I can not open any web page anymore, I get timeout for all connections.
I found temporary solution by restarting network manager as mentioned in this answer
sudo systemctl restart network-manager.service
This behaviour only started recently, like 2 weeks ago (maybe bug in one of the updates?), before I had no problems. VPN connection itself is not problematic since it works without problems on different OSs.
Same problem happens if I suspend and resume.
How can I debug and resolve this issue?