This document includes references to the support tool SLAnalyzer. For more information see: What is SLAnalyzer?
In SLAnalyzer select Tools->Advanced Authentication->Remote Admin->Manage external URLs
This option will update the AA server policy “Public external URLs (load balancers)”. In AA version 6.4.3.2 the server was updated to restrict access based on incoming domains. Only domains listed in this policy are allowed to access the server.