Go to the EC2 dashboard and right-click FortiGate 1. Select Instance State > Stop to stop this instance.
Connect via RDP to the Windows server. All connections use the subnet for FortiGate 2.
You can also connect using your ELB's DNS name. Connections only use the subnet for FortiGate 2.
Start FortiGate 2 and wait until ELB status is 2/2. Connect to the server using multiple sources.
The load is balanced between the FortiGate-VM instances.