HA led active on standalone FG40F

[Nkom]

I have a FG40F that I have some trouble with. Sometimes it stops working and it has to be rebooted.
I have noticed that when the device works the HA led is green, but the box is a standalone device. When it stops working the HA led is not active. 
So I wonder if there is a connection. 

[fricci_FTNT]

Hi @Nkom ,

When you say "it stops working", what do you mean? Please provide more details, that is too general.
1- Does FortiGate still process some traffic when the issue happens?
2- Can you access it? Or can you access its console at least?
3- Does it look completely frozen?

4- Are there other blinking lights when the issue happens? Which coulour?
5- Which FOS version are you currently running? Have you upgraded FOS recently?
6- Does the issue happen regularly, at specific time of the day or just randomly? How often it happens?
7- Have you noticed any particular triggering condition? For example if there is more traffic than usual, or if a specific action/change that you make on the FortiGate can trigger the issue?
8- What is the current HA config from CLI? (show system ha)

Have you noticed anything in terms of performances or in "diag debug crashlog read" output at the time/date of the issue?

Best regards,