We have to connect to untrusted machines via PowerShell. To do this, you have to add the machines,

First, if you have settings in there run this command to get a backup:

$trustedhosts = get-Item -Path WSMan:\localhost\Client\TrustedHosts

Then to get them to modify:

$trustedhosts.value

copy that out, add your hosts to it with comma delimited and add it with powershell:

Set-Item WSMan:\localhost\Client\TrustedHosts -Value 'Server2,Server2'

To use it in code (so it doesn’t ask you if you’re sure), you can force it by using the -Force switch

Set-Item WSMan:\localhost\Client\TrustedHosts -Value 'Server2,Server2' -Force

then check again:

get-Item -Path WSMan:\localhost\Client\TrustedHosts