Sometimes it’s hard to know which physical NIC matches up to a Virtual NIC in VMware ESXi. You can find out which physical NIC is being used by your VM by making the NIC light flash with Ethtool. Ethtool is a linux based command line software that can help you find which physical NIC maps to which NIC name in ESXi.
To use Ethtool, download it to the ESXi host and run ethtool -p vmnicx 10, where x is the VM NIC you want to make blink and 10 is the number of seconds you want it to blink. For example, to make VM NIC 1 blink for 3 seconds, run the following command:
ethtool -p vmnic1 3
It should then be fairly easy to find which physical NIC, VM NIC 1 is mapped to in ESXi.