system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What in the world does Gateway Timed Out mean?

I mean, what the heck is a gateway in the first place.
gpt
When you contact a website, you rarely make a connection directly with the server you're trying to get information from. Your connection is often routed through a series of intermediary servers that "route" the traffic, they serve different purposes such as load balancing, filtering out spam and serving faster traffic in different locations, these servers are referred to gateway servers, as they are just "gateways" on the the way to your destination.

If one of these servers fails to contact its destination, but you managed to make a connection to the gateway, it will respond with a 504 Gateway Timeout.

This just means the gateway responded to you, but was unable to help you connect to the next gateway or destination.