Powershell add VPN IKEv2 with LE certificates for Windows 10/11

addvpn.ps1

# This script will download LE intermediate CA and install it in a computer,
# create IKEv2 vpn connection with SplitTunneling, -DnsSuffix and -RememberCredential
# USAGE
# Open Powershell as administarton and run next line:
# PowerShell.exe -ExecutionPolicy Bypass -File .\addvpn.ps1
# where "addvpn.ps1" is the name of this script

# Define the parameters for the VPN connection (change it)
$Name = "NAME_OF_VPN_CONNECTION"
$ServerAddress = "SERVER_ADDRESS"
$DnsSuffix = "DNS_SUFFIX"

# Define the certificate URL
$CertificateUrl = "https://letsencrypt.org/certs/lets-encrypt-r3.der"
$BaseDir = Join-Path $home "Downloads"
$CertName = $CertificateUrl.Substring($CertificateUrl.LastIndexOf("/") + 1)
$OutFile = Join-Path $BaseDir $CertName

Write-Host "Creating VPN connection with name '$Name', server address '$ServerAddress', and DNS suffix '$DnsSuffix'"
Write-Host "Downloading certificate from '$CertificateUrl' to '$OutFile'"

# Check if the certificate file already exists
if (!(Test-Path $OutFile)) {
    # Downloads certificate
    try {
        Invoke-WebRequest -Uri $CertificateUrl -OutFile $OutFile
    } catch {
        Write-Host $_.Exception | format-list -force
    }
}

# Install certificate
Write-Host "Installing certificate from '$OutFile'"
try {
    Import-Certificate -FilePath $OutFile -CertStoreLocation Cert:\LocalMachine\CA
    Write-Host "Successfully installed certificate"

    # Delete the certificate file
    Write-Host "Deleting downloaded certificate file '$OutFile'"
    Remove-Item $OutFile
} catch {
    Write-Error "Failed to install certificate: $_"
    exit 1
}

# Create a VPN connection
try {
    Add-VpnConnection -Name $Name -ServerAddress $ServerAddress -TunnelType Ikev2 -RememberCredential -SplitTunneling -DnsSuffix $DnsSuffix -EncryptionLevel "Required" -PassThru
} catch {
    Write-Error "Failed to create VPN connection: $_"
    exit 1
}