Administrative Domains : ADOM device modes
 
ADOM device modes
An ADOM has two device modes: normal and advanced. In normal mode, you cannot assign different FortiGate VDOMs to multiple FortiManager ADOMs. The FortiGate unit can only be added to a single ADOM.
In advanced mode, you can assign different VDOMs from the same FortiGate unit to multiple ADOMs.
 
Advanced ADOM mode will allow users to assign VDOMs from a single device to different ADOMs, but will result in a reduced operation mode and more complicated management scenarios. It is recommended for advanced users only.
To change the ADOM mode, go to System Settings > Advanced > Advanced Settings and change the selection in the ADOM Mode field.
Alternatively, use the following command in the CLI:
config system global
set adom-mode {normal | advanced}
end
Normal mode is the default setting. To change from advanced back to normal, you must ensure no FortiGate VDOMs are assigned to an ADOM.