If you are deploying the VM-Series firewall with interfaces enabled in Layer 3 mode, make sure to enable use of hypervisor assigned MAC addresses so that the hypervisor and the firewall can properly handle packets. Alternatively, use the Hyper-V Manager to enable MAC address spoofing on the virtual network adapter for each dataplane interface on the firewall. For more information, see Hypervisor Assigned MAC Addresses.

If you are deploying the VM-Series firewall with interfaces enabled in Layer 2 mode or virtual-wire mode, you must enable MAC address spoofing on the virtual network adapter in Hyper-V for each dataplane interface on the firewall. This setting is required to ensure that packets sent by the VM-Series are not dropped by the virtual network adapter if the source MAC address does not match the outgoing interface MAC address.