Fortinet have opened up their technical training program for free online here: https://www.fortinet.com/training/cybersecurity-professionals.html?utm_source=pr&utm_campaign=2020-q2-keyword
This includes NSE4 and above now.
Previously only for the partner community self paced training material has been available via the partner portal but Fortinet have now opened this up to the public.
Get in there if you want to increase your knowledge of Fortigate and the other related Fortinet platforms.
Fortinet training for free!