In FortiOS, specific administrative features are hidden by default within the Graphical User Interface (GUI) to simplify the administrative experience. To route SD-WAN traffic based on specific applications (application steering), the FortiGate relies on its Application Control engine. If the "Application Control" feature is disabled in the GUI visibility settings, the option to select an application as a destination in an SD-WAN rule will not appear. An administrator must navigate to System > Feature Visibility and toggle "Application Control" on. Once enabled, the "Application" and "Application Group" selection fields will dynamically appear in the SD-WAN rule configuration page.

A. Application-based routing is fully supported and highly recommended in Direct Internet Access (DIA) setups to intelligently steer specific SaaS or web applications over optimal ISP links.

B. FortiGate natively supports the configuration of application-based SD-WAN rules in both the Command Line Interface (CLI) and the GUI, provided the feature is set to visible.

C. You do not need to enable GUI feature visibility via the CLI. The standard and intended method to expose hidden GUI elements is through the System > Feature Visibility GUI menu.

Fortinet, Inc. FortiOS 7.2 Administration Guide. Section: System > Feature Visibility. (Details the hiding and exposing of advanced security profiles, including Application Control, in the web interface).

Fortinet, Inc. FortiOS 7.2 Administration Guide. Section: SD-WAN > SD-WAN Rules. (Documenting the prerequisite of enabling Application Control visibility to utilize application steering in priority rules).