Fixing a problem with SMTP TLS connection

Fixing a problem with SMTP TLS connection

Hey, I built an SMTP server on Centos 7 VPS using Webmin and I installed Mailwizz Application, But when I want to add my server to Mailwizz I get this message

• Connection could not be established with host mail.domain.net :stream_socket_client(): unable to connect to tcp://mail.-domain.net:587 (Connection refused)
  Log data:
  ++ Starting Swift_SmtpTransport
  !! Connection could not be established with host mail.domain.net :stream_socket_client(): unable to connect to tcp://mail.domain.net:587 (Connection refused) (code: 0)

I guess Its a TLS problem, if anyone can help me with it I will very appreciate it (My budget is limited at the moment, so I hope you regard the price)

Requirements

Very Good with Webmin and TLS AND SSL Problems
Able to work on Anydesk (I want to see how it will be fixed so I can fix it the next time myself)

Skills Required

vmin
webmin
mail
mailwizz
smtp
tls
ssl