Hi,
when you have NAT configured, both VMs will get an DHCP IP from your PC, not your router. They will communicate with your VMnet8 LAN adapter, that was installed by VMware workstation. Both VMs will communicate with each other with the NAT standard settings.
Your router will only give them a DHCP address when you use bridged mode ( and of course your router is configured to give addresses to anyone on the network ).
Solution for you:
look at this kb-article: VMware KB: Disabling the VMware DHCP Service on the Host Computer
and:
1. Keep the NAT configuration.
2. Disable the VMware DHCP
3. set the windows server to a static IP
4. configure the Windows Server DHCP to give an IP to your second VM.
5. profit 
Regards