FortiClient WAN optimization supports protocol optimization and byte caching in IPsec VPN and SSL VPN tunnels between FortiClient and a FortiGate unit. To add WAN optimization to FortiClient, configure FortiClient Advanced settings and enable WAN optimization. This setting can then apply WAN optimization to any IPsec or SSL VPN tunnel between FortiClient and FortiGate, if the FortiGate IPsec or SSL VPN configuration also includes WAN optimization.

When FortiClient with WAN optimization enabled attempts to connect a server-side FortiGate unit, FortiClient automatically detects if WAN optimization has been added to the FortiGate tunnel configuration. If WAN optimization is detected and FortiClient can successfully negotiate with the FortiGate unit, WAN optimization starts.