Hi,

VMware vSphere does only allow to set MAC Addresses from the Range 00:50:56:00:00:00 up to 00:50:56:3f:ff:ff. You can set a static MAC out of this range but cannot start the virtual machine. The typical error message is:

Invalid MAC address specified. 12:34:6:78:90:12 is not an allowed static Ethernet address. It conflicts with VMware reserved MACs.
Continue reading ESXi: Cannot start VM. Invalid MAC address specified. 12:34:6:78:90:12 is not an allowed static Ethernet address →