Email form

I tried both options from the documentation and I am getting this error:

Email could not be sent due to some Unexpected Error. Please Try Again later.

Reason:
SMTP connect() failed. https://github.com/PHPMailer/PHPMailer/wiki/TroubleshootingSMTP server error: Failed to connect to server SMTP code: 111 Additional SMTP info: Connection refused

this is my form.php

<?php

/*-------------------------------------------------

Form Processor Plugin
by SemiColonWeb

---------------------------------------------------*/

/-------------------------------------------------
PHPMailer Initialization
---------------------------------------------------/

use PHPMailer\PHPMailer\PHPMailer;
use PHPMailer\PHPMailer\Exception;

require 'phpmailer/src/Exception.php';
require 'phpmailer/src/PHPMailer.php';
require 'phpmailer/src/SMTP.php';

/-------------------------------------------------
Receiver's Email
---------------------------------------------------/

$toemails = array();

$toemails[] = array(
'email' => 'placeholderemail', // Your Email Address
'name' => 'placeholdername' // Your Name
);

/-------------------------------------------------
Sender's Email
---------------------------------------------------/

$fromemail = array(
'email' => 'no-reply@website.com', // Company's Email Address (preferably currently used Domain Name)
'name' => 'Company Name' // Company Name
);

/-------------------------------------------------
reCaptcha
---------------------------------------------------/

// Add this only if you use reCaptcha with your Contact Forms
$recaptcha_secret = ''; // Your reCaptcha Secret

/-------------------------------------------------
hCaptcha
---------------------------------------------------/

// Add this only if you use hCaptcha with your Contact Forms
$hcaptcha_secret = ''; // Your hCaptcha Secret

/-------------------------------------------------
PHPMailer Initialization
---------------------------------------------------/

$mail = new PHPMailer();

/* Add your SMTP Codes after this Line */
$mail->IsSMTP();
$mail->Host = "mail.oncprofessional.com";
$mail->SMTPDebug = 0;
$mail->SMTPAuth = true;
$mail->SMTPSecure = "ssl";
$mail->Port = 26;
$mail->Username = "placeholderemail";
$mail->Password = "placeholderpassword";

// End of SMTP

/-------------------------------------------------
Form Messages
---------------------------------------------------/

$message = array(
'success' => 'We have successfully received your Message and will get Back to you as soon as possible.',
'error' => 'Email could not be sent due to some Unexpected Error. Please Try Again later.',
'error_bot' => 'Bot Detected! Form could not be processed! Please Try Again!',
'error_unexpected' => 'An unexpected error occured. Please Try Again later.',
'captcha_invalid' => 'Captcha not Validated! Please Try Again!',
'captcha_error' => 'Captcha not Submitted! Please Try Again.'
);

/-------------------------------------------------
SPAM Protection Settings
---------------------------------------------------/

$spam_keywords = array(
'viagra',
'cialis',
'levitra'
);

$allowed_urls = 1;

/-------------------------------------------------
Form Processor
---------------------------------------------------/

if( $_SERVER['REQUEST_METHOD'] == 'POST' ) {

$prefix		= !empty( $_POST['prefix'] ) ? $_POST['prefix'] : '';
$submits	= $_POST;
$botpassed	= false;

$message_form					= !empty( $submits['message'] ) ? $submits['message'] : array();
$message['success']				= !empty( $message_form['success'] ) ? $message_form['success'] : $message['success'];
$message['error']				= !empty( $message_form['error'] ) ? $message_form['error'] : $message['error'];
$message['error_bot']			= !empty( $message_form['error_bot'] ) ? $message_form['error_bot'] : $message['error_bot'];
$message['error_unexpected']	= !empty( $message_form['error_unexpected'] ) ? $message_form['error_unexpected'] : $message['error_unexpected'];
$message['captcha_invalid']	= !empty( $message_form['captcha_invalid'] ) ? $message_form['captcha_invalid'] : $message['captcha_invalid'];
$message['captcha_error']		= !empty( $message_form['captcha_error'] ) ? $message_form['captcha_error'] : $message['captcha_error'];

/*-------------------------------------------------
	Bot Protection
---------------------------------------------------*/

if( isset( $submits[ $prefix . 'botcheck' ] ) ) {
	$botpassed = true;
}

if( !empty( $submits[ $prefix . 'botcheck' ] ) ) {
	$botpassed = false;
}

if( $botpassed == false ) {
	echo '{ "alert": "error", "message": "' . $message['error_bot'] . '" }';
	exit;
}

/*-------------------------------------------------
	SPAM Protection
---------------------------------------------------*/

function spam_keyword_check( $submitted, $spamwords ) {
	if( is_array( $submitted ) ) {
		return false;
	}
	if( !is_array( $spamwords ) ) $spamwords = array( $spamwords );
	foreach( $spamwords as $spamstring ) {
		if( ( $position = stripos( $submitted, $spamstring ) ) !== false ) return $position;
	}
	return false;
}

function spam_url_check( $submitted ) {
	if( is_array( $submitted ) ) {
		return false;
	}

	$pattern = "/(http|https)\:\/\/(www\.)?[a-zA-Z0-9\-\.]+\.[a-zA-Z]{2,3}(\/\S*)?/";

	if( preg_match_all( $pattern, $submitted, $urls ) ) {
		return count($urls);
	}

	return false;
}

foreach( $submits as $spam_submit ) {
	if( spam_keyword_check( $spam_submit, $spam_keywords ) || spam_url_check( $spam_submit ) > $allowed_urls ) {
		// A successful message is displayed to the submitter that makes him think that the Form has been sent so that he cannot modify the keywords to prevent SPAM
		echo '{ "alert": "success", "message": "' . $message['success'] . '" }';
		exit;
	}
}

/*-------------------------------------------------
	reCaptcha
---------------------------------------------------*/

if( isset( $submits['g-recaptcha-response'] ) && !isset( $submits['h-captcha-response'] ) ) {

	$recaptcha_data = array(
		'secret' => $recaptcha_secret,
		'response' => $submits['g-recaptcha-response']
	);

	$recap_verify = curl_init();
	curl_setopt( $recap_verify, CURLOPT_URL, "https://www.google.com/recaptcha/api/siteverify" );
	curl_setopt( $recap_verify, CURLOPT_POST, true );
	curl_setopt( $recap_verify, CURLOPT_POSTFIELDS, http_build_query( $recaptcha_data ) );
	curl_setopt( $recap_verify, CURLOPT_SSL_VERIFYPEER, false );
	curl_setopt( $recap_verify, CURLOPT_RETURNTRANSFER, true );
	$recap_response = curl_exec( $recap_verify );

	$g_response = json_decode( $recap_response );

	if ( $g_response->success !== true ) {
		echo '{ "alert": "error", "message": "' . $message['captcha_invalid'] . '" }';
		exit;
	}
}

/*-------------------------------------------------
	hCaptcha
---------------------------------------------------*/

if( isset( $submits['h-captcha-response'] ) ) {

	$hcaptcha_data = array(
		'secret' => $hcaptcha_secret,
		'response' => $submits['h-captcha-response']
	);

	$hcap_verify = curl_init();
	curl_setopt( $hcap_verify, CURLOPT_URL, "https://hcaptcha.com/siteverify" );
	curl_setopt( $hcap_verify, CURLOPT_POST, true );
	curl_setopt( $hcap_verify, CURLOPT_POSTFIELDS, http_build_query( $hcaptcha_data ) );
	curl_setopt( $hcap_verify, CURLOPT_SSL_VERIFYPEER, false );
	curl_setopt( $hcap_verify, CURLOPT_RETURNTRANSFER, true );
	$hcap_response = curl_exec( $hcap_verify );

	$h_response = json_decode( $hcap_response );

	if ( $h_response->success !== true ) {
		echo '{ "alert": "error", "message": "' . $message['captcha_invalid'] . '" }';
		exit;
	}
}

$template	= !empty( $submits['template'] ) ? $submits['template'] : 'html';
$html_title	= !empty( $submits['html_title'] ) ? $submits['html_title'] : 'Form Response';
$forcerecap	= ( !empty( $submits['force_recaptcha'] ) && $submits['force_recaptcha'] != 'false' ) ? true : false;
$replyto	= !empty( $submits['replyto'] ) ? explode( ',', $submits['replyto'] ) : false;

if( $forcerecap ) {
	if( !isset( $submits['g-recaptcha-response'] ) ) {
		echo '{ "alert": "error", "message": "' . $message['captcha_error'] . '" }';
		exit;
	}
}

/*-------------------------------------------------
	Auto-Responders
---------------------------------------------------*/

$autores	= ( !empty( $submits['autoresponder'] ) && $submits['autoresponder'] != 'false' ) ? true : false;
$ar_subject	= !empty( $submits['ar_subject'] ) ? $submits['ar_subject'] : 'Thanks for your Email';
$ar_title	= !empty( $submits['ar_title'] ) ? $submits['ar_title'] : 'Its so good to hear from You!';
$ar_message	= !empty( $submits['ar_message'] ) ? $submits['ar_message'] : 'Autoresponder Message';

preg_match_all('#\{(.*?)\}#', $ar_message, $ar_matches);
if( !empty( $ar_matches[1] ) ) {
	foreach( $ar_matches[1] as $ar_key => $ar_value ) {
		$ar_message = str_replace( '{' . $ar_value . '}' , ( is_array($submits[ $ar_value ]) ? implode( ', ', $submits[ $ar_value ] ) : $submits[ $ar_value ] ), $ar_message );
	}
}

$ar_footer	= !empty( $submits['ar_footer'] ) ? $submits['ar_footer'] : 'Copyrights © ' . date('Y') . ' **SemiColonWeb**. All Rights Reserved.';

$mail->Subject = !empty( $submits['subject'] ) ? $submits['subject'] : 'Form Response from your Website';
$mail->SetFrom( $fromemail['email'] , $fromemail['name'] );

if( !empty( $replyto ) ) {
	if( count( $replyto ) > 1 ) {
		$replyto_e = $submits[ $replyto[0] ];
		$replyto_n = $submits[ $replyto[1] ];
		$mail->AddReplyTo( $replyto_e , $replyto_n );
	} elseif( count( $replyto ) == 1 ) {
		$replyto_e = $submits[ $replyto[0] ];
		$mail->AddReplyTo( $replyto_e );
	}
}

foreach( $toemails as $toemail ) {
	$mail->AddAddress( $toemail['email'] , $toemail['name'] );
}

/*-------------------------------------------------
	All Processing for Fields starting with
	Underscore must be done before this line of code
---------------------------------------------------*/

$underscore = array();

foreach( $submits as $name => $value ) {
	if( strpos($name, '_') === 0 ) {
		$underscore[] = $name;
	}
}

$unsets = array( 'prefix', 'subject', 'replyto', 'template', 'html_title', 'message', 'autoresponder', 'ar_subject', 'ar_title', 'ar_message', 'ar_footer', $prefix . 'botcheck', 'g-recaptcha-response', 'h-captcha-response', 'force_recaptcha', $prefix . 'submit' );

$unsets = $unsets + $underscore;

foreach( $unsets as $unset ) {
	unset( $submits[ $unset ] );
}

$fields = array();

foreach( $submits as $name => $value ) {
	if( empty( $value ) ) {
		continue;
	}

	$name = str_replace( $prefix , '', $name );
	$name = function_exists('mb_convert_case') ? mb_convert_case( $name, MB_CASE_TITLE, "UTF-8" ) : ucwords($name);

	if( is_array( $value ) ) {
		$value = implode( ', ', $value );
	}

	$fields[$name] = nl2br( filter_var( $value, FILTER_SANITIZE_SPECIAL_CHARS ) );
}

$files = $_FILES;

foreach( $files as $file => $filevalue ) {
	if( is_array( $filevalue['name'] ) ) {
		$filecount = count( $filevalue['name'] );

		for( $f = 0; $f < $filecount; $f++ ) {
			if ( isset( $_FILES[ $file ] ) && $_FILES[ $file ]['error'][ $f ] == UPLOAD_ERR_OK ) {
				$mail->IsHTML(true);
				$mail->AddAttachment( $_FILES[ $file ]['tmp_name'][ $f ], $_FILES[ $file ]['name'][ $f ] );
			}
		}
	} else {
		if ( isset( $_FILES[ $file ] ) && $_FILES[ $file ]['error'] == UPLOAD_ERR_OK ) {
			$mail->IsHTML(true);
			$mail->AddAttachment( $_FILES[ $file ]['tmp_name'], $_FILES[ $file ]['name'] );
		}
	}
}

$response = array();

foreach( $fields as $fieldname => $fieldvalue ) {
	if( $template == 'text' ) {
		$response[] = $fieldname . ': ' . $fieldvalue;
	} else {
		$fieldname = '<tr>
							<td style="font-size: 16px; line-height: 24px; font-weight: bold; padding: 0 0 5px 0;" align="left">' . $fieldname . '</td>
						</tr>';
		$fieldvalue = '<tr>
							<td style="font-size: 16px; line-height: 24px; color: #777777; padding: 0 15px 30px 0;" align="left">' . $fieldvalue . '</td>
						</tr>';
		$response[] = $fieldname . $fieldvalue;
	}
}

$referrer = $_SERVER['HTTP_REFERER'] ? '<br><br><br>This Form was submitted from: ' . $_SERVER['HTTP_REFERER'] : '';

$html_before = '<table border="0" cellpadding="0" cellspacing="0" height="100%" width="100%" bgcolor="#eeeeee" style="width: 100%; height: 100%; padding: 50px 0 50px 0;">
			<tr>
				<td align="center" valign="top">
					<table border="0" cellpadding="0" cellspacing="0" width="84%" bgcolor="#ffffff" style="width: 84%;">
						<tr>
							<td align="center" valign="top">
								';

$html_after = '</td>
						</tr>
					</table>
				</td>
			</tr>
		</table>';

if( $template == 'text' ) {
	$body = implode( "<br>", $response ) . $referrer;
} else {
	$html = $html_before . '<!-- / Header -->
								<table border="0" cellpadding="0" cellspacing="0" width="84%" style="width: 84%;">
									<tr>
										<td style="padding: 30px 0 30px 0; border-bottom: solid 1px #eeeeee; font-size: 30px; font-weight: bold; text-decoration: none; color: #000000;" align="left">
											' . $html_title . '
										</td>
									</tr>
								</table>

								<!-- / Sub-Header -->
								<table border="0" cellpadding="0" cellspacing="0" width="84%" style="width: 84%; padding: 60px 0 30px 0;"">
									' . implode( '', $response ) . '
								</table>

								<!-- / Footer -->
								<table border="0" cellpadding="0" cellspacing="0" width="100%" align="center">
									<tr>
										<td align="center">
											<table border="0" cellpadding="0" cellspacing="0" width="84%" align="center" style="border-top: 1px solid #eeeeee; width: 84%;">
												<tr>
													<td style="color: #d5d5d5; text-align: center; font-size: 12px; padding: 30px 0 30px 0; line-height: 22px;">' . strip_tags( $referrer ) . '</td>
												</tr>
											</table>
										</td>
									</tr>
								</table>
								' . $html_after;

	$body = $html;
}

if( $autores && !empty( $replyto_e ) ) {
	$autoresponder = new PHPMailer();

	/* Add your Auto-Responder SMTP Codes after this Line */

	// End of Auto-Responder SMTP

	$autoresponder->SetFrom( $fromemail['email'] , $fromemail['name'] );
	if( !empty( $replyto_n ) ) {
		$autoresponder->AddAddress( $replyto_e , $replyto_n );
	} else {
		$autoresponder->AddAddress( $replyto_e );
	}
	$autoresponder->Subject = $ar_subject;

	$ar_body = $html_before . '<!-- / Header -->
				<table border="0" cellpadding="0" cellspacing="0" width="84%" style="width: 84%;">
					<tr>
						<td style="padding: 30px 0 30px 0; border-bottom: solid 1px #eeeeee; font-size: 30px; font-weight: bold; text-decoration: none; color: #000000;" align="left">
							' . $ar_title . '
						</td>
					</tr>
				</table>

				<!-- / Sub-Header -->
				<table border="0" cellpadding="0" cellspacing="0" width="84%" style="width: 84%; padding: 60px 0 30px 0;"">
					<tr>
						<td style="font-size: 16px; line-height: 26px; color: #777777; padding: 0 15px 30px 0;" align="left">' . $ar_message . '</td>
					</tr>
				</table>

				<!-- / Footer -->
				<table border="0" cellpadding="0" cellspacing="0" width="100%" align="center">
					<tr>
						<td align="center">
							<table border="0" cellpadding="0" cellspacing="0" width="84%" align="center" style="border-top: 1px solid #eeeeee; width: 84%;">
								<tr>
									<td style="color: #d5d5d5; text-align: center; font-size: 12px; padding: 30px 0 30px 0; line-height: 22px;">' . $ar_footer . '</td>
								</tr>
							</table>
						</td>
					</tr>
				</table>
				' . $html_after;

	$autoresponder->MsgHTML( $ar_body );
	$autoresponder->CharSet = "UTF-8";
}

$mail->MsgHTML( $body );
$mail->CharSet = "UTF-8";
$sendEmail = $mail->Send();

if( $sendEmail == true ):

	if( $autores && !empty( $replyto_e ) ) {
		$send_arEmail = $autoresponder->Send();
	}

	echo '{ "alert": "success", "message": "' . $message['success'] . '" }';
else:
	echo '{ "alert": "error", "message": "' . $message['error'] . '<br><br>**Reason:**<br>' . $mail->ErrorInfo . '" }';
endif;

} else {
echo '{ "alert": "error", "message": "' . $message['error_unexpected'] . '" }';
}