WinRM cannot process the request

Solution: Start the service WinRM with WMI

function StartWinRM
{
    Param([string] $Computer,
    [System.Management.Automation.PSCredential] $Credential)

    $service = Get-WmiObject -ComputerName $Computer -Credential $Credential -Class Win32_Service -Filter "Name='WinRM'"
    $service.StartService()
}