There are many HTML error codes for failed Web page loading, but one of the most misunderstood is "Error 504: Gateway Timeout." Unlike 404, which simply indicates that data is not at that IP address, a gateway timeout can indicate other problems.
The data and Web pages for every site posted on the Internet exist on a physical computer, which connects to the Internet through a server or router. This router is known as the gateway, and any data requests sent to that website have to pass through the site's associated server. A data request can also pass through multiple servers, especially if the two interacting systems are located far from one another.
During a normal query, your computer sends a request for data through your ISP, transfers to the destination server, then processes and returns the requested data to you within a few seconds. If a Web server is experiencing heavy traffic, the server bandwidth may not be able to handle the load and therefore, exceeds the time for data packet transfer. Alternatively, the server could be down.
When you encounter a 504 error, you really can't do anything about it because the problem is with the server. However, the gateway timeout can also occur with the use of a proxy server, which prevents the URL of the website from resolving into an IP address. You can try using a different proxy.
To determine where the problem starts, try accessing another website. It's unlikely that you'll get the same error. You can also use the "tracert" command to a Web page to determine the pathway a data request takes. To run a tracert command, type "cmd" in the search bar of the Windows "Start" menu on your computer, press "Enter" and type the text "tracert