WNDR3700v4: How to block an IP address

I want to block an IP address from being accessed from my LAN. The instructions that I have found indicate setting up a static route. But, after entering the IP address, sub mask of 255.255.255.255 and the gateway IP adress equal to the router itself (as it is my gateway to the WAN) and rebooting the router, the IP address is not blocked as I can ping the IP from my server.

The IP address I want to block doesn't have a name associated with it, so I can't use the parental control section.

Thanks for any tips in getting this to work.

Firmware: V1.0.2.102