networking - Where to add the Pre-Shared Key for the Server Authentication with Network Manager for L2TP/IPSEC? - Ask Ubuntu
Site-to-Site IKEv2 IPSec VPN using Pre-Shared Key Authentication - simple configuration example for two Cisco routers - NIL - Network Information Library
PKI IPSec VPN - SRX to SRX - Multi SA - YouTube
Zyxel USG - Firewalls
Configuring GroupVPN with IKE using Preshared Secret on the WAN Zone