Most drivers and Wi-Fi chips require the U/L bit to be 1 for a locally assigned address. If you set the first octet to a value where that bit is 0 (e.g., 00:... , 02:... , 04:... , etc., depending on the exact hex), the driver rejects the change as invalid. For example, 00:11:22:33:44:55 fails because 00 in binary ends with ...00000000 — bit 1 (second least significant) is 0.
(where x is any hex digit) will typically bypass this restriction. Stack Overflow Quick Fixes If you are using a tool like Technitium MAC Address Changer or the Windows Registry, try these steps: Most drivers and Wi-Fi chips require the U/L
This is likely a translation artifact from a driver’s internal English string or an older tool’s grammar error. The intended meaning: "Set the first octet for this change to work." (where x is any hex digit) will typically
: Some adapters are hardware-locked and will not allow changes regardless of the prefix. How to Fix It depending on the exact hex)
Click the "Value" radio button and type a 12-digit hex string. Ensure the second digit is 2, 6, A, or E .
The first three octets (first six hex digits) represent the , which identifies the manufacturer of the network card. The first octet also contains two special "flag" bits: