In this article, I suggest you a simple solution with Mikrotik router (MikroTik L2TP with IPsec VPN). Then, you can connect to your work network from outside the office.
This article explains the configuration of site to site VPN where both sites have a static public IP on the WAN interface. The following are the IP address information of both FortiGates.
This article explains how to configure the IPSec VPN Client to site feature on Fortigate device. so that the devices can be accessed and remote local area network safely.
