The System Engineers of BOLL Engineering have been supporting Fortigate devices for 18 years. This year, FortiOS v6.4 was released and we have again gathered all the troubleshooting commands that we use regularly in our new CheatSheet.
Hopefully this CheatSheet will help you as well.
You will find the most important commands on the first page. The second page contains troubleshooting commands for problems with firewall policies and security profiles, followed by the third page with commands for network problems. The last page covers system and hardware commands and general information.
Updated to v1.1 (addition and correction for FortiToken, 11.12.2020)