I am trying to activate Windows 10 LTSB machines against a 2012 R2 KMS server. I have installed the KMS role on the server along with my 2012 datacenter KMS key which should be sufficient for activating a Windows 10 client.
However, when my clients try to activate, they are getting the error message that the key was already used on another device, and it appears as though it is trying to activate with a MAK key.
It doesn't even look like it is trying to activate against the KMS server. My office 2016 activations are working without an issue.
I'm not sure what needs to be done to make this think look at the KMS server for the activation or to be sure that it is looking at the kms server for activation.