Manage Untrusted Servers in Server Manager

NTLM authentication will be used for hosts in untrusted domains or in a workgroup which will require the host to be added to the machine running Server Manager's TrustedHost list. Check the current value of TrustedHosts using the following:

(get-item wsman:localhostclienttrustedhosts).value

If the return result is not a * which means anyone is trusted add the new host you want to manage to the list of trusted hosts using the following (where server1 and server2 are new hosts to be managed):

$trustedhosts = (get-item wsman:localhostclienttrustedhosts).valueset-item wsman:localhostclienttrustedhosts -value "$trustedhosts,server1,server2" 

If the remote server to be managed is a workgroup machine, you need to enable elevation of processes for the non-Administrator account using the following:

New-ItemProperty -Name LocalAccountTokenFilterPolicy -path HKLM:SOFTWAREMicrosoftWindowsCurrentVersionPoliciesSystem -propertyType DWord -value 1

If the target machine is not connected to a domain network you might need to manually enable the Windows Remote Management (HTTP-In) firewall exception for the connected network (on a workgroup machine this could be the Public network).

Right-click the server, which will show a Kerberos target resolution error, and select the Manage As ... action.Enter the credential to use. If the server is in a workgroup, include the workgroup name (e.g., workgroupadministrator) then the password and click OK.