Separate subnets in the same network Question.

I have a network with 3 credit card machines and a DVR and nothing else. The port forwarding causes a PCI Compliance scan fail. The credit card company wants the subnets to be different on the credit card machines and the dvr (all credit card machines on 192.168.1.xx and the dvr on something else). The internet modem is an att unit from att. The tech I spoke to that works where they do the PCI scans said I could make a network diagram if I change the subnet on the DVR and they could manually bypass the scan fail status but I still need to forward ports to access the dvr outside the network. Can I make the ip address different without additional equipment and what would be an example ip, gateway and subnet?