If you want to configure the FortiGate-VM to operate in transparent mode, you must configure the VMware ESXi server's virtual switches to operate in promiscuous mode to allow traffic that is not addressed to the FortiGate-VM to pass through it.
- In the vSphere client, select your VMware server, and then select the Configuration tab.
- In Hardware, select Networking.
- Select Properties of vSwitch0.
- In the Properties window, select vSwitch, and then select Edit.
- Select the Security tab, set Promiscuous Mode to Accept, and then select OK.
- Select Close.
- Repeat steps 3 to 6 for other virtual switches that the FortiGate-VM uses.