OpenVPN Support Forum

Scenario: To use the physical ethernet adapter's MAC address with the TAP Adapter

Result: After assigning the physical ethernet adapter's MAC address with the TAP Adapter, we verify it on our DHCP Server that the MAC address of the TAP Adapter registered is the TAP Adapter's MAC address and not the Physical ethernet adapter's MAC address. This works as expected with an older version of TAP Adapter that is included in OpenVPN version 2.4.4.

We can not use the latest version of OpenVPN with our solution because of this issue.

Is there anyone that can help with this issue?

The setting of user values is (to a degree) still discussed on GitHub issue.
Sounds like the MAC is required to be a "locally administered address" (bit 2 of byte 1 is set) due to Windows driver signing restrictions (?).

A workaround for you may be to change BOTH (TAP and physical MACs) to a valid user-assigned value (current drivers should support this).