Client

PS C:\Windows\system32> Get-ChildItem -Path WSMan:\localhost\Client


   WSManConfig: Microsoft.WSMan.Management\WSMan::localhost\Client

Type            Name                           SourceOfValue   Value
----            ----                           -------------   -----
System.String   NetworkDelayms                                 5000
System.String   URLPrefix                                      wsman
System.String   AllowUnencrypted                               false
Container       Auth
Container       DefaultPorts
System.String   TrustedHosts                                   *

Auth

PS C:\Windows\system32> Get-ChildItem -Path WSMan:\localhost\Client\Auth


   WSManConfig: Microsoft.WSMan.Management\WSMan::localhost\Client\Auth

Type            Name                           SourceOfValue   Value
----            ----                           -------------   -----
System.String   Basic                                          true
System.String   Digest                                         true
System.String   Kerberos                                       true
System.String   Negotiate                                      true
System.String   Certificate                                    true
System.String   CredSSP                                        false

TrustedHosts

Specifies the list of remote computers that are trusted. Other computers in a workgroup or computers in a different domain should be added to this list.

Set the TrustedHosts list

winrm set winrm/config/client '@{TrustedHosts="serverA,serverB,serverC"}'
winrm set winrm/config/client '@{TrustedHosts ="10.40.30.103"}'
winrm set winrm/config/client '@{TrustedHosts ="[fe80::9d5b:8d26:5f86:2a2f]"}'
winrm set winrm/config/client '@{TrustedHosts ="*"}'
winrm set winrm/config/client '@{TrustedHosts =""}'
Get-ChildItem -Path  WSMan:\localhost\Client\TrustedHosts

Set-item WSMan:\localhost\Client\TrustedHosts -Value "192.168.0.*" -Concatenate
Set-item WSMan:\localhost\Client\TrustedHosts -Value *
Set-item WSMan:\localhost\Client\TrustedHosts -Value ''