Error:

Exchange Management Shell commands work. Enable PsRemoting done, assigned role no issues, but when we try to connect the Exchng Plugin get this error.
"Connecting to remote server. server .server .com failed with the following error message : The WinRM client cannot process the request. It cannot determine the content type of the HTTP response from the destination computer. The content type is absent or invalid. For more information, see the about_Remote_Troubleshooting Help topic."

Fix.

Please configure Configure the Trusted Hosts under WinRM Client under Local Security Policy. Type Local Group Policy by clicking on Windows Key or type gpedit.msc in Windows+R.
When it opens Click on Computer Configuration--->Administrative Templates---->Windows Components---->Windows Remote Management(WinRM)-->and click on WinRM Client.
Here on the right plane you will find the option "Trusted Hosts". If it is "Not Configured". Double click on it and click on "Enabled" then click on Apply & save the setting.