If you restart the router, or factory reset it, does the fan come on during the self test that it runs on bootup?
Usually when the Netgear routers that have a fan, the fan profiles are set where the fan almost never comes on.
Also if the router was ever used in a dusty environement, or has a lot of visible dust on the fan blades, try using an air duster, or even a vacuum cleaner hose to see if you can induce some airflow that will cause the fan to spin (only allow it to spin slowly to see if it is able toturn freely). The reason for this, is in rare cases, if dust builds up within the fan hub area, or if the fan has gotten stiff over time, that can prevent the initial movement needed to get a low torque brushless DC motor spinning.
non-industrial case fans tend to be very low torque since their use cases typicaly only need a tiny amount of torque.
Thats for you to login to your router but will enable netgear so called secret menu where will have option to see if the fan is turmed off or if its only set to come on certain temp etc.....
