If the GUI method is failing, the command line can sometimes provide more information and push the activation through.
If you want, I can provide the specific KB updates and registry changes needed to enable TLS 1.2 on Windows Server 2008 R2 and the exact certificate names to look for. windows server 2008 r2 activation error 0x80072f8f work
Check date/time and time zone
Windows needs up-to-date root certificates to verify the digital signatures of Microsoft’s servers. If your certificates are years out of date, the connection will be blocked as untrusted. If the GUI method is failing, the command
Have you already tried the method?