I've found that Windows KMS clients (2012R2 specifically but may be others) try to talk to MS servers during activation. My understanding was that this should be entirely local.
slmgr /ipk GGWHX-.....-.....-.....-DJ6PQ
slmgr /skms 10.10.10.10:1688
slmgr /ato
Our servers have very limited access outside our network I've found that the above produces a 0x80072ee2 error unless a proxy server is specified. This has caught me out as I often configure the proxy settings soon after building servers. On this particular server, it is not allowed to have a proxy configured.
Any ideas how to get 2012R2 to activate against an internal KMS server without access to MS via the Internet?
Thanks
The key you've started to list there does not appear to be a KMS client key. You should not install a key on the client if it is going to be KMS activated. The OS image from Microsoft ships with the client KMS key pre-installed - it is the same for every computer of that OS on the planet.
If you've already changed some clients from the default, you can change them back using the keys here: https://technet.microsoft.com/en-us/library/jj612867(v=ws.11).aspx
For reference, the KMS client key for 2012 R2 Datacenter is
W3GGN-FT8W3-Y4M27-J84CP-Q3VJ9
And the Standard edition key is:D2N9P-3P6X9-2R39C-7RTCD-MDVJX