# Get current TrustedHosts value
$current = (Get-Item WSMan:\localhost\Client\TrustedHosts).Value

# Add new host, keeping any existing entries
$new = "$current,192.168.3.166"

# Remove any accidental double commas or leading/trailing commas
$new = ($new -split ',' | Where-Object { $_ -and $_ -ne '' } | Select-Object -Unique) -join ','

# Set TrustedHosts with the combined list
Set-Item WSMan:\localhost\Client\TrustedHosts -Value $new