Asp.net Failure sending mail after enabling TLS1.2

I have windows dedicated server hosting more than 20 websites all built using asp.net. All my sites were sending emails using Gmail SMTP perfectly, but 2 days ago I asked tech-support to enable TLS1.2 and disable TLS1.0; when this happened all the emails stopped!

I have tried all solutions Here but still no use! Finally, I tried to use another email provider instead of Gmail and the emails are sent successfully.

Does anybody know what happens to Gmail services with TLS1.2?