Old stand alone device FortiGate 100D- how to set management FQDN instead of IP?

Are you seeing the lagging when you try to connect to the device through a browser or with Fortimanager?  IF with the browser, the FQDN should not matter as long as your DNS is resolving properly, there is not setting in the fortigate to tell it what its external FQDN is.  The port you are resolving the FQDN to should be setup with HTTPS for management, FMG is just for Fortimanager access to the device.

hi distillednetwork, thank you for your reply.
This is happening when I browse the FW through browser, I also have this issue on another forti device (also stand alone, this time 240D).
I also suspect this could be some kind of DNS issue, but not sure how this should be resolved, this is why I think the forti should be set with this FQDN as management.
Is there a way to set hosts file record for forti? I'm open to any suggestions on this issue

Tnx

hi distillednetwork,

I have tried that already, even when I set the FQDN in my Hosts file, it is not working well.

There is some minor improvement, however when I browse through the interface pages its still lagging and I also get sometimes notification saying "Lost Connection to Foritgate - Attempting to reconnect" and than it disappears after few seconds and keep working.

This is not happening when I access the web interface by IP, only with FQDN.
This is why I think it could be some kind of internal DNS resolution within the Forti device itself, which led me to think the FQDN should be set as the management FQDN somewhere.

Hi,

I have found the issue eventually,

Turns out that our Corp IT department had started to implement SSL decryption by our anti-virus without me knowing on it, once we excluded the FQDN from it all started to work smoothly.

Tnx all for your help