- Opened the properties of my test NIC.
- Opened the Internet Protocol Version 4 (TCP/IPv4) properties.
- Click "Advanced"
- Uncheck the box that says "Automatic Metric" and enter a high number. I used 500.
- Hit OK multiple time to close the dialog boxes and apply the setting.
Now, when Windows needs a path, it will see the high metric and use the production NIC. My production VMs will only see the NIC I assign to to them (the test NIC with the high metric) and won't have any choice but to use the test interface for outgoing traffic.