I have some problem when send email, the message like this
" Failed to send mail, error reason [(454, b'4.7.0 Temporary authentication failure: Connection lost to authentication server", but when i use rouncube its normally, and why my roundcube always get notification

and notification connection to the storage server failed,
but after I refreshed the page it returned to normal but then when I refreshed it it repeated again

Hello, check if the configuration of roundcube is correct? Replace 135roundcubemail.com with your domain name
Modify this file:
/www/wwwroot/135roundcubemail.com/config/config.inc.php
Add the following:
$config['enable_installer'] = true;
Then browser access: http://135roundcubemail.com/installer/?_step=1
Final test setup