Error: "The WinRM client cannot complete the operation within the time specified" (4235364)

The OCS/Lync Servers and Users task fails with one of the following errors:

"The following error occurred during the processing of a given gathering: Starting a command on 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"

OR

"The following error occurred during the processing of a given gathering: 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"