Fortigate3100D to Fortigate500E Link
i want to connect two Fortigates directly to each other, because for a fallback scenario I need a direct link. Therefore I thought, I put them together via SFP multimode and configure an IP address on both sides. But the Link doesn't come up. There are no failures on Layer 1, neither cables or SFPs. So it seems to be a wrong configuration. My theory is that both Fortigates are waiting for a signal of connection or initialising.
If I put the physical ports into a vSwitch it doesn't work neither.
Is there a special config I need?
Greetings from Germany,