Hi Greg Lyon,
On a brand new Windows 11 device, especially one provided by an OEM like Dell, the built-in Administrator account is disabled by default and cannot be activated without existing administrative rights. The net user administrator /active:yes command requires elevated privileges to succeed, so if you are running it from a standard account, the change will not persist after reboot. This is expected behavior and not a bug.
To resolve this, you will need to sign in with an account that already has administrative rights, or contact your IT administrator if the device is domain-joined. If this is a personal machine, you should use the account created during the initial Windows setup, which is typically granted admin privileges. From there, you can enable the built-in Administrator account if needed, or create a new local administrator account.
You can try and let me know the result. If this explanation helps clarify the situation, please hit “Accept Answer” so I know your issue is resolved.
Jason.