Who Me Too'd this topic

I am trying to block an IP range of some idiot in Singapore who keeps trying to interrogate my development server.

So, I have gone to Advanced -> Security -> Block Services to add a new rule.

Selected Service Type ALL, TCP/UDP, Port 1 to Port 65535, Service Type ALL

Clicked IP Address Range:

This is where the fun begins, for the range I have tried:
114.119.151. to 114.119.151. = invalid IP address (fair enough)
114.119.151.0 to 114.119.151.255 = invalid IP address
114.119.151.1 to 114.119.151.255 = invalid IP address
114.119.151.1 to 114.119.151.254 = invalid IP address
114.119.151.10 to 114.119.151.200 = invalid IP address

Any ideas anyone? - Or is it that I am trying to block Netgear Singapore LMAO...