Trying to federate server using this guide for 10.5.1:
Federate an ArcGIS Server site with your portal—Portal for ArcGIS (10.5.x) | ArcGIS Enterprise
Running into this issue...
"The server at 'https://[internal machine address]6443/arcgis/admin/security/config/update' returned an error. Failed to update the security configuration. Cannot update security configuration to federate with Portal as server is not registered with Portal. Could not connect to the ArcGIS Server on machine '[Internal machine address]'.The ArcGIS Server service on that machine may not be running or the machine may not be reachable at this time."
I am a bit confused because the current documentation does not mention registering a server with Portal prior to attempting federation. Is there a step or process I am possibly missing?