I have a weird problem with my VPN(l2tp/IPSec) recently.
At first when I added the VPN there was no problem but when i changed my WiFi connection (came home from work!) the blocked sites that i visited in my previous network weren't responding any more, everything else works fine for example I tried a blocked website that i have never visited and it works fine.
I tried cleaning my dns cache but no result + tried ping no result tried deleting VPN connection and adding it after I joined the network.
Worked at first but not anymore (I am a software engineer i know its weird but it happened).
I tried other vpn protocols(open vpn, cisco) and all of them have this problem.
I use 20.04 version