I'm using PowerShell to send ZPL to a ZD421.  

Sending the ZPL works correctly, but I'm unable to get a response ($reader.ReadToEnd() line).

Here's the code:

function Out-ZplPrinter {
    param (
        [Parameter(Mandatory,ValueFromPipeline)]
        [string]$Command,
        
        [Parameter(Mandatory)]
        [string]$IpAddress,
        
        [int]$Port = 9100
    )
    
    try {
    
        [System.Net.Sockets.TcpClient]$client = [System.Net.Sockets.TcpClient]::new()
        $client.Connect($IpAddress, $Port)
    
        [System.IO.StreamWriter]$writer = [System.IO.StreamWriter]::new($client.GetStream())
        [System.IO.StreamReader]$reader = [System.IO.StreamReader]::new($client.GetStream())
    
        # send the ZPL
        $writer.Write($Command)
        $writer.Flush()
    
        # read the response
        $response = $reader.ReadToEnd() # <--- hangs here
        return $response
    
    } 
    catch {
        Write-Host "ERROR: $( $_.Exception.Message )" -ForegroundColor Red
    }
    finally {
        if ($null -ne $reader) {
            $reader.Close()
            $reader.Dispose()
        }
    
        if ($null -ne $writer)
        {
            $writer.Close()
            $writer.Dispose()    
        }
    
        if ($null -ne $client)
        {
            $client.Close()
            $client.Dispose()    
        }
    }
}
# send a label to the ZD421
"^XA^FO235,25,0^FDFIRST LAST^FS^XZ" | Out-ZplPrinter '192.168.19.112'

What am I missing?