Wake On LAN

Hi BackerTheHacker,

Wake-On-LAN uses broadcast packets as seen from the packet captures on https://wiki.wireshark.org/WakeOnLAN.md.

To enable the Forwarding of Broadcast packets over the IPsec tunnel, you will need to add a new Phase 2 selector for the IPSec tunnel, then enable broadcast forward on the IPSec tunnel interface and also create a multicast policy for the same.

The below KB explains the same:
Technical Tip: How to configure FortiGate forward broadcast
https://community.fortinet.com/t5/FortiGate/Technical-Tip-How-to-configure-FortiGate-forward-broadcast/ta-p/197533

Technical Tip: Broadcast traffic over site-to-site IPsec VPN
https://community.fortinet.com/t5/FortiGate/Technical-Tip-Broadcast-traffic-over-site-to-site-IPsec-VPN/ta-p/194666

I hope it will help you.