A factory (or hard) reset brings your F-Secure SENSE back to factory settings, the same state as when the device was first turned on. All your settings and firmware version are erased and restored to factory default values. You will need to reconnect your devices to the SENSE network.
Follow these steps if performing a normal reset on the router has not helped:
Unplug the power cable from the F-Secure SENSE router.
Press and hold down the Reset button at the back of the router.
While holding down the Reset button, plug the power cable back into the router.
Keep holding the Reset button until the letters "FF" appear on the SENSE router display. This initiates the factory reset, which can take a few minutes. The device restarts once the reset is done.