FortiManager disconnects from my FortiGates = No routing between VDOMS

Hi,

I have over 10 Fortigates connecting to my FortiManager due to no internet connection. I have validated them using entitlement files, all working great until i lose connection to the manager (After about 2hrs, no routing between VDOMS).  I need these still to work at least for 10 days if no connection to the Manager, is this possible or if i lose the connection will i lose routing between VDOMS due to the license being un-validated (when i use the CLI: "get system status" it states for the license: Warning) Also what is the default time settings for the FortiGate validating the license with the Manager?

Appreciate any feedback

steve