Hi,
Welcome to the community, and i would like to know if your VMs got an IP address or not ? because it is not clear. Then , do you have some event on your DHCP server ? maybe try to simply restart your DHCP? and delete all your old reservations. Because if it is working with a new nic (as you say , a new mac address is generated) i think you need to delete all your reservations address on your DHCP scope (for your VMs) and restart your DHCP.
Regards,
Julien