Perhaps the fingerprint machine has a specific ip address built into its firmware and that address is not in your current subnet. Check the fingerprint machine to see if it has an ip address or look at its user manual to determine how to change its address.
You could change the ip address on the fingerprint machine to one in the dhcp range or you could assign the fingerprint machine a reserved dhcp address (works like a static address within the dynamic range) by entering the fingerprint machine MAC address in the router's reserved dhcp table and select an address within the dynamic assignment range that is not already assigned. From then on, the FM will always be assigned that address and will be within the subnet.