Hi @Glenn Maxwell ,
After my search, your problem should be related to the Default Web Site and Exchange Back End certificate binding in IIS. You can check whether the correct certificate is bound.
If you have selected the correct certificate , change the SSL Settings of powershell to ignore.
The following are some similar cases that you can refer to:
https://www.reddit.com/r/exchangeserver/comments/462ra8/exch2013server2012_cannot_connect_to_ems/
https://hope-this-helps.de/serendipity/archives/Exchange-2013-Powershell-Error-FailureCategoryCafe-SendFailure-FullyQualifiedErrorId-2144108477-493.html
https://community.spiceworks.com/topic/2118477-cannot-connect-to-my-exchange-servers-with-the-exchange-managment-shell
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If the solution above not help, please check the application log in event viewer to get more related information.
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