# NATVM Credential
$LoginUser = "Administrator"
$LoginPass = "NATVMPassword"

$Sstr = ConvertTo-SecureString $LoginPass -AsPlainText -Force
$psc  = New-Object System.Management.Automation.PsCredential($LoginUser, $Sstr)
$Cred = Get-Credential -Credential $psc

#create nat vSwitch
$SubnetPrefix = "192.168.255.0/24"
New-VmSwitch "vNAT-01" -SwitchType NAT -NatSubnetAddress $SubnetPrefix
New-NetNat -Name "VmNAT-01" -InternalIPInterfaceAddressPrefix $SubnetPrefix

$VM = Get-VM -Name 'NATVM'
# Change vSwitch
Connect-VMNetworkAdapter -VMNetworkAdapter (Get-VMNetworkAdapter -VM $VM -Name 'Nic2') -SwitchName 'vNAT-01'

# Change IPAddress
Invoke-Command -VMId $VM.VMId -ScriptBlock { Get-NetIPAddress -AddressFamily IPv4 | Where-Object {$_.IPAddress -eq "ExternalIPAddress" } } -Credential $Cred
Invoke-Command -VMId $VM.VMId -ScriptBlock { Remove-NetIPAddress -InterfaceIndex 3 -AddressFamily IPv4 -DefaultGateway "ExternaGWAddress" -Confirm:$false  } -Credential $Cred
Invoke-Command -VMId $VM.VMId -ScriptBlock { Set-DnsClientServerAddress -InterfaceIndex 3 -ResetServerAddresses -Confirm:$false  } -Credential $Cred
Invoke-Command -VMId $VM.VMId -ScriptBlock { New-NetIPAddress -InterfaceIndex 3 -IPAddress "192.168.255.10" -AddressFamily IPv4 -PrefixLength 24 -DefaultGateway "192.168.255.1" -Confirm:$false  } -Credential $Cred