Raspbian L2TP/IPsec VPN Server with Raspberry Pi

For this post, I'm using Raspberry Pi 3 with Raspbian 9.3 with Kernel 4.9
There are several tutorials that you can find online. e.g. https://www.raspberrypi.org/forums/viewtopic.php?t=31541

However, you may get the error message: The L2TP-VPN server did not respond. Try reconnecting. If the problem continues, verify your settings and contact your Administrator.

The error is with the newest Openswan which breaks down the support with Raspbian.

To fix this, we have to install the older version of Openswan. Just remove your Openswan and install the older version with the following commands.

$ wget http://snapshot.raspbian.org/201403301125/raspbian/pool/main/o/openswan/openswan_2.6.37-3_armhf.deb
$ sudo dpkg -i openswan_2.6.37–3_armhf.deb

$ /etc/init.d/xl2tpd restart # restart the service
$ /etc/init.d/ipsec restart