Thanks for your response Sanjeev.
here is the full error log:
`Versions:
WordPress: 5.6.2
WordPress MS: No
PHP: 5.6.40
WP Mail SMTP: 2.6.0
Params:
Mailer: smtp
Constants: No
ErrorInfo: SMTP connect() failed. https://github.com/PHPMailer/PHPMailer/wiki/Troubleshooting
Host: smtp.mail.yahoo.com
Port: 587
SMTPSecure: tls
SMTPAutoTLS: bool(true)
SMTPAuth: bool(true)
Server:
OpenSSL: OpenSSL 1.0.2u 20 Dec 2019
Debug:
Mailer: Other SMTP
SMTP connect() failed. https://github.com/PHPMailer/PHPMailer/wiki/Troubleshooting
SMTP Debug:
2021-03-02 01:03:24 Connection: opening to smtp.mail.yahoo.com:587, timeout=300, options=array()
2021-03-02 01:03:25 Connection failed. Error #2: stream_socket_client(): unable to connect to smtp.mail.yahoo.com:587 (Connection refused) [/home/atsgroup/public_html/wp-includes/PHPMailer/SMTP.php line 381]
2021-03-02 01:03:25 SMTP ERROR: Failed to connect to server: Connection refused (111)
SMTP connect() failed. https://github.com/PHPMailer/PHPMailer/wiki/Troubleshooting`
I hope this problem could solve soon.