How to force Freenas to connect to only one domain controller?

Question

FreeNAS

Good day! The essence of the question is how to force us to hammer only one domain controller. and then he is still hammering on another, which is not available. In what settings to register it. In the webmord, only one controller is selected. But we are being scanned by everything.
How can I force him not to knock on others, but only on the main one.