It looks like you are using the same port 443 for GUI access and SSL-VPN. You may try to change the SSL-VPN port (VPN> SSL-VPN Settings) if it is not used to something else like 444 and try this again.
You can also set the certificate via CLI if there is a bug in the GUI:
config system global set admin-server-cert "Fortinet_GUI_Server" <-- choose the cert, tab will rotate the options
- Emirjon If you have found a solution, please like and accept it to make it easily accessible for others.
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