You need a 2012r2 KMS key to activate both hosts and clients at 8.1 level, do you have a valid SA on your 2012 license? Otherwise you will have to use a different host for KMS duties.

Microsoft has confirmed that Windows 7 and 8 keys can no longer activate any Windows 11 edition or version, not just Canary builds, as reported in September. However, Windows 10 keys are still valid.