Re: Time Offset sent as DHCP option 2 not correct
☄ Helpfulby ede_pfau 2019/06/02 03:04:39
I've been back and forth with Fortinet support on this. It's been definitely determined that when a FGT DHCP Server Time Zone option is set to a time zone that observes DST, the DHCP Server will send the time zone offset adjusted for DST in DHCP Option 2. Fortinet support's stance at the moment is that this is "correct" and to "turn off DST handling on your client device"
I'm trying to get support to understand that this is not the industry standard on how DST offsets are handled. DST offset is intended to be handled by the client device, not server side, and they should always send a time zone offset based on standard time.
I've also explained that there is no way to properly set DHCP Option 2 myself and override their behavior. You can't do it in the GUI whatsoever. You can do it in the CLI but if you ever try to modify the Interface settings in the GUI it will not let you save until you delete the DHCP Option 2 parameter.
As of now, the only way to make sure any devices that is picking up DHCP Option 2 in order to calculate it's time offset is to turn off DST handling on the device or set the time zone on the DHCP server to be 1 hour slower during DST calendar period (ie. if you are in eastern time, choose central time as the time zone when we are in DST).