Logging in to LMS using BrainCert subdomain takes forever to sign in. If you are using CLoudFlare SSL proxy with external domain, you will see "Error 524" timeout issues when signing in.
This may happen when you have an improperly configured custom SMTP mail relay setting and the feature to notify admin is turned on in 'Account & Settings' --> 'User registration' --> 'Notifications'.
To fix login timeout issues, turn off account notifications to "No" for the above e-mail triggers.
Go to, 'Account & Settings' --> 'Mail Relay' and check "Yes" to use BrainCert Mail Server.
Turning off all account related email notifications is recommended when setting up or troubleshooting custom mail server related issues.