FortiOS ships with a full-featured custom DynDNS2 client via the "genericDDNS" server type. With DNS Beacon your FortiGate stays reachable under a permanent hostname even when your WAN IP changes. Here's the setup.
Network → DNS → Dynamic DNS
FortiOS 6.x and later support the "genericDDNS" server type, which calls the standard DynDNS2 /nic/update endpoint on any server you specify. In the CLI: `config system ddns` → `set ddns-server genericDDNS`, `set ddns-server-addr` with the API address, `set ddns-domain` with your hostname, `ddns-username` / `ddns-password` for authentication. Set the monitor-interface to your WAN interface.
Create a free DNS Beacon account, add a hostname and generate an API key — then come back and finish the setup above.
Create free account