Local Subnet scan

Just purchased Mac Scanner Pro and after the demoing i guess i didn't look close enough but it only scans local subnets. i need to be able to scan IP ranges across my WAN is this possible?

 

MAC scanner is working based on ARP protocol.
Arp protocol is a layer 2 protocol which can not be routed.

Multi-subnet segments mean there must be a router working as gateway to route traffics.

Arp can not go across multi-subnet segments because it can not be routed by routers.

This means to scan across subnets by ARP is not possible.
Colasoft MAC Scanner is designed to show user the hosts in a flat earth mode networks.

To scan across subnets, you need to have software scan by routable protocols eg. layer 3 protocols.