Mailer error: SMTP connect() failed

I’m stuck at an error sending mail to the user. I am using VPS Centos 7, and running php web using phpmailer to proceed with sending mail as below structure. It works perfectly fine when running on xampp localhost, but when I run on Centos I get Mailer error: SMTP connect() failed . I tried everything but still can’t fix it, I tried commenting the line $mail->isSMTP(true); it works, but no email is sent to the client. I also tried checking port 587, 25, and 465 to see if it listens via telnet : telnet stmp.gmail.com 587(25,465) and the result is 220. I also installed phpmailer on centos, but not sure why it won’t connect to stmp server. Hope everyone can help me with this problem.

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

require_once "../vendor/autoload.php";

            $mail = new PHPMailer;
            $mail->isSMTP(true);
            $mail->Host = "smtp.gmail.com";
            $mail->SMTPAuth = true;
            $mail->Username = "my_email@gmail.com";
            $mail->Password = "my_password";
            $mail->Port = 587;
            $mail->IsHTML(true);
            $mail->CharSet = 'UTF-8';
            $mail->From = "my_email@gmail.com";
            $mail->FromName = "No Reply";
            $mail->Subject = $subject;
            $mail->Body = $body;
            $mail->AddAddress($email_to);

            if (!$mail->send()) {
			$error = 'Mail error: '.$mail->ErrorInfo; 
                echo 'send_mail_failed';
				print_r($error);
				
				
            } else {
                $update_password_byEmail = "UPDATE account SET password=:gen_password WHERE name=:currentUser AND email=:currentEmail;";
                $stmt_gen_pass_update = $sqlWeb->prepare($update_password_byEmail);
                $stmt_gen_pass_update->bindValue(':gen_password', md5($password_generate));
                $stmt_gen_pass_update->bindValue(':currentUser', $usernameOfEmail);
                $stmt_gen_pass_update->bindValue(':currentEmail', $target_email);
                $stmt_gen_pass_update->execute();
                $stmt_gen_pass_update->closeCursor();

                echo 'send_mail_successful';
            }
        } else {
		$error = 'Mail error: '.$mail->ErrorInfo; 
            echo 'send_mail_error';
			//echo $error;
        }