I was taken a look to the information you shared via the bnsupport tool.
I don't see anything weird in terms of CPU or memory usage, nor a huge number of website accesses. Therefore, I think we can discard your issue is related to performance issues.
I also took a look to your Apache log file (the one available at
/opt/bitnami/apache2/logs/error_log) and the MySQL log file (the one available at
/opt/bitnami/mysql/data/mysqld.log) and there's nothing relevant there either.
That said, I think the issue comes from Moodle, the website application itself.
Could you share the IP of your AWS server so I can browse and see what kind of responses does it give me?
Could you also please ensure the error persist when accessing your site using a different computer or a "incognito" window in your browser?