Powershell and Connection Closure

#Create Time Stamp
$time = Get-Date
    ForEach ($server in (Import-CSV 'C:\output\servers.csv')){

        #Test the port by checking to see if it is open and listening
        write-host 'Testing connectivity to SQL server on', $server.name
        $servername=$server.name
        $socket = new-object System.Net.Sockets.TcpClient($server.ip,$server.port)
        # $? variable means to check what happened in the last operation and it's success or failure
            if ($?)
                {
                
                    
                $socket.close()
                $socket.dispose()
	            Start-Sleep -s 1
                }
            Else
                {
                $socket.close()
                $socket.dispose()
                
                Write-Host "Sending Email"

                #SMTP server name
                $smtpServer = "[redacted]"

                 #Creating a Mail object
                $msg = new-object Net.Mail.MailMessage

                 #Creating SMTP server object
                $smtp = new-object Net.Mail.SmtpClient($smtpServer)

                #Email structure 
                $msg.From = "[redacted]"
                $msg.ReplyTo = "[redacted]"
                $msg.To.Add("[redacted]")
                $msg.subject = "SAP Connection Failed"
                $msg.body = $server,' Has failed SQL Connectivity'

                #Sending email 
                $smtp.Send($msg)
	            Write-Host $servername ,'s SQL connection has failed. Current time is: ', $time
                Start-Sleep -s 300
                }
        }

This is the code I am working with.

The issue is when I check netstat these connections stay open for quite some time before closing. Is there any way to forcibly close the connection after it is finished?