As a prerequisite to using this guide, and before continuing, you must make sure that you have successfully set up your own IPsec VPN server, and upgraded Libreswan to the latest version due to CVE-2019-10155. This for advanced users only. Other users please use IPsec/L2TP or IPsec/XAuth mode.
A few years ago, I’ve found this gem which allow us to set up our own IPsec VPN server with L2TP, XAuth and IKEv2 on Ubuntu, Debian and CentOS distro.