You're going to have to explain in more detail how this is configured. There's no such thing as a "Moodle load balancer". You would need multiple Moodle instances in a cluster. You can then use a reverse proxy (e.g. haproxy) or just DNS round robin to access them. Pointing at the same DB instance (and shared file storage) is a given. So, I have no idea what you are doing....
Hardware and performance
504 Gateway Error in Load Balancer
This discussion has been locked so you can no longer reply to it.