FortiClient is used to add endpoint control to devices located within a security fabric. This is done by creating a FortiClient Profile that only allows traffic from compliant devices to flow through the FortiGate.
In a security fabric, FortiClient profiles are applied by the first FortiGate that a device's traffic flows through, which is often an ISFW FortiGate, rather than the Upstream FortiGate. Information about the FortiClient device's registration and on-net status will appear only on the FortiGate that applies the FortiClient profile.
For more information about FortiClient profiles, see the Security Profiles handbook.