Gateway lists are useful when using FortiClient EMS integrated with FortiGate. If using FortiClient EMS without FortiGate, you are not required to use gateway lists.
You can use gateway lists to specify what IP addresses or FQDNs and ports endpoints can use to connect FortiClient Telemetry to FortiGate, EMS, or FortiGate and EMS. You can create one or more gateway lists and assign them to domains or workgroups.
After deploying FortiClient to endpoints, FortiClient uses the gateway list to try and connect FortiClient Telemetry to FortiGate or EMS. This connection is based on the gateway list received from EMS.
Even if the endpoint is already connected to a FortiGate, you can still assign a gateway list to endpoints. You can also update existing gateway lists as required. EMS pushes the updates to endpoints with the next Telemetry communication.