In the system logs, the following error was experienced throughout:
Log Name: System
Date: 28/09/2017 7:24:32 AM
Event ID: 15021
Task Category: None
An error occurred while using SSL configuration for endpoint 0.0.0.0:444. The error status code is contained within the returned data.
When attempting to open Exchange Management Shell, the following error was experienced.
VERBOSE: Connecting to exchange.domain.local.
New-PSSession : [exchange.domain.local] Connecting to remote server exchange.domain.local failed with the following error message : [ClientAccessServer=EXCHANGE,BackEndServer=exchange.domain.local,RequestId=3c48101b-0062-4799-b902-07b2b634321c,TimeStamp=28/09/2017 12:47:18 AM] [FailureCategory=Cafe-SendFailure] For more information, see the about_Remote_Troubleshooting Help topic.
At line:1 char:1
+ New-PSSession -ConnectionURI "$connectionUri" -ConfigurationName Microsoft.Excha ...
+ CategoryInfo : OpenError: (System.Manageme....RemoteRunspace:RemoteRunspace) [New-PSSession], PSRemotin
+ FullyQualifiedErrorId : -2144108477,PSSessionOpenFailed
If we look at the error, it was complaining about SSL on 0.0.0.0:444. This is the Exchange Backend Website, the frontend website listens on 0.0.0.0:443.
We fired up IIS Manager, checked the backend website and looked at the SSL Binding. There was no certificate attached for some reason.
I just re-attached the backend certificate, the default self signed certificate generated by the Exchange installation process is fine.