Perform the following steps to validate the connectivity between this server and the AD FS service. Ensure that the firewall ...

Perform the following steps to validate the connectivity between this server and the AD FS service. 
  1. Ensure that the firewall between this server and the AD FS service is configured accurately.
  2. Ensure that DNS resolution for the AD FS service name appropriately points to the AD FS service that resides within the corporate network. This can be achieved through a DNS server that serves this server in the perimeter network or through entries in the HOSTS files for the ADFS service name.
  3. Validate the network connectivity by opening up the browser on this server and accessing the federation metadata endpoint which is at https:///federationmetadata/2007-06/federationmetadata.xml
  4. If this issue still persists, please contact Microsoft support to troubleshoot this issue in your environment.