Unable to send email using php mailer

Hello Zoho team,
I am trying to configure email on my website but getting the following error:

2018-10-21 05:35:39 Connection: opening to smtp.zoho.com:587, timeout=300, options=array()

2018-10-21 05:35:40 Connection failed. Error #2: stream_socket_client(): unable to connect to smtp.zoho.com:587 (Connection refused) [/home/vikashjhakash/vikashtech.com/vendor/phpmailer/phpmailer/src/SMTP.php line 325]

2018-10-21 05:35:40 SMTP ERROR: Failed to connect to server: Connection refused (111)

SMTP connect() failed. https://github.com/PHPMailer/PHPMailer/wiki/Troubleshooting

Mailer Error: SMTP connect() failed. https://github.com/PHPMailer/PHPMailer/wiki/Troubleshooting

I have used the following code.. please suggest me a solution for the same

<?php

use PHPMailer\PHPMailer\PHPMailer;

require 'vendor/autoload.php';

$txt = "<html>

<head>

<title>M/s VIKASH TECH</title>

</head>

<body>

Name - ".$_POST['name']."<br/>

Email - ".$_POST['email']."<br/>

Number - ".$_POST['number']."<br/>

Message - ".$_POST['message']."<br/>

</body>

</html>

$mail = new PHPMailer;

$mail->isSMTP();

$mail->SMTPDebug = 4;

$mail->Host = 'smtp.zoho.com';

$mail->Port = 587;

$mail->SMTPAuth = true;

$mail->SMTPSecure = 'tls';

$mail->Username = ' support@vikashtech.com';

$mail->Password = '---mypassword---';

$mail->setFrom(' support@vikashtech.com', 'M/s VIKASH TECH');

$mail->addAddress(' support@vikashtech.com', 'M/s VIKASH TECH - Support Team');

$mail->addAddress($_POST['email']);

$mail->Subject = "Contact Request";

//$mail->Body = $_SESSION['msg'].$_SESSION['otp'].$_SESSION['note'];

$mail->msgHTML($txt, __DIR__);

if (!$mail->send()) {

echo 'Mailer Error: ' . $mail->ErrorInfo;

} else {

echo 'OK';

}