FG200D - 5.2.4 : HELP! How to allow Office365 (Exchange Online Migration)

Hello Everyone,

Apologies in advance. I'm very new to firewalls, especially Fortigate. Our office is currently migrating to Exchange Online.

Users are currently seeing the SSL certificate coming from FG200 when they try to access the Exchange Online.

I have gone through the MS O365 allowing the FQDN from the FG200D, source <LAN> destination <WAN>

I haven't tested it though but it would be good if someone could lead me to the right direction in solving this issue.

Attached are the screenshot of the errors for reference.

Cheers