Cannot contact host FQDN while connecting esxi host to vCenter

Products

• VMware vSphere ESXi

Issue/Introduction

Attempting to connect a esxi host to vCenter yeilds the red banner error "Cannot contact host FQDN while connecting esxi host to vCenter"

Environment

all versions of vCenter and esxi

Cause

Environmental network devices like firewall and wan optimizers can use technology like ssl inspection to modify the traffic between esxi and vCenter

 

This can be proven using the below steps

From the esxi host run the following command to validate the hash of the certificate in use by the esxi host: 

cat /etc/vmware/ssl/rui.crt

 

From vCenter run the following command: 

openssl s_client -connect esxifqdn:443

 

If the hash in both of these commands do not match, a firewall or wan optimizer is modifying the traffic between host and vCenter

Resolution

Change the network configuration so that the traffic between esxi and vCenter isn't being modified.