Connect to Gmail SMTP

After registration of our domain to cloudflare we cannot connect to Gmail SMTP. Our website is developed on wordpress and we are using POST SMTP plugin to connect to Gmail SMTP. Can you please help me to fix the issue as soon as possible. Thank you

What’s the hostname you’ve set the plugin to connect to? I see that the plugin has logging. What do the logs say?

Our hosting called site5 and the error is connection failure.