I came across this error during an Exchange deployment in one of the Universities of Canada :). The EMC would not connect:

“The attempt to connect to http://server.domain.com/PowerShell using “Kerberos” authentication failed: connecting to remote server failed with the following error message : The WinRM client cannot complete the operation within the time specified. Check if the machine name is valid and is reachable over the network and firewall exception for Windows Remote Management service is enabled. For more information, see the about_Remote_Troubleshooting Help topic.”

There are some blog posts on the internet around how to fix the connectivity problem to the server, but none of them were working in my case.

In my situation, the server EMC was pointing to the server that didn’t come back after reboot (but this is another story). EMC would connect fine to a different working server.

As a workaround I’ve added a “new” Exchange forest and was managed to connect, but I wanted to actually fix the issue.

So, the solution is simple :).

Close EMC

Execute the following commands (in CMD):

DEL "%USERPROFILE%\AppData\Roaming\Microsoft\MMCDEL "%USERPROFILE%\AppData\Roaming\Microsoft\MMC\Exchange Management Console.*"
REG DELETE HKEY_CURRENT_USER\Software\Microsoft\ExchangeServer\v14\AdminTools /v NodeStructureSettings /f

Now, the EMC correctly rediscover an active Exchange server..