The FortiGate 100D is a legacy firewall that is now officially end-of-life (EOL) and does not support the latest FortiOS releases. For users still operating this hardware, the "best" firmware is generally considered to be the most stable version within the v6.2 release train, as newer mainlines like v6.4 or v7.x are not compatible with the Recommended Firmware Versions
The 100D has a decent resale value on eBay because of its ASIC chips. Sell it and buy a FortiGate 60F or 80F. The cost of a breach on an EOL device is higher than the cost of a new firewall. Fortigate 100d Firmware Download BEST
But for home labs, legacy networks, or test environments? FortiGate 100D on v5.4.13 is still the best firewall you can get for under $100. The FortiGate 100D is a legacy firewall that
get system statusbeyond FortiOS 6.2. It cannot run FortiOS 6.4, 7.0, or newer. Security Note: CLI: get system status GUI: Dashboard > System
Best Firmware Version for FortiGate 100D