504 gateway timeout error does indicate the actual problem is with the server or an network error between the servers.

Where this kind of error has got nothing to do with your PC internet connection.504 error which simply says the server is unavailable right now

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Common Causes are as follows :

Server is down for maintenance
Server is overloaded to handle your request

503 Bad gateway error is a kindergarten type of problem. If your website gives out 502 and 503 server errors, then you must go back to the sandbox and learn the basics.