Unable to activate Windows 10.

Recently I upgraded my hardware to meet Windows 11 criteria. Although I moved my Windows 10 drive to my new hardware, my system reported Windows was not active. I executed the process of hardware change to activate but was met with "servers down" to perform this operation. I eventually caved and purchased a new license for Windows 11.

I made a VHDX of my Windows 10 environment and can run it in HYPER-V. It still shows it is inactive. I tried entering the license key and it came back with the license wasn't a valid license. This came from the original box of Windows 10 Pro when I purchased it.

I also tried the command prompt functions of

slmgr /upk,

slmgr /ipk <YourProductKey>, and slmgr /ato which also met with failure.

I would like to know how to activate my legitimate copy of Windows.