Today I ran into a problem with IPsec Xauth PSK and the built-in Android VPN client (Android 4.1.2), resulting in some sites (such as www.yahoo.com) not loading through the VPN tunnel. Turns out I was dealing with MTU issues. When the Android VPN is started, it sets the MTU to 1500 on the tun0 interface: $ … Continue reading MTU woes in IPsec tunnels and how you can fix it