The API will timeout server-side after five minutes.
High plausibility of the gpt-3.5-x AI response for your account being a low production rate though, as others have reported they have been randomly selected for.
You can use streaming completions to see how fast you are receiving tokens.
You can also then use a watchdog timer that retries if there is a period of non-response.
As a solution, I fragment the content and send a request with a maximum of 500 tokens. It works for now, but I still continue to get a 503 error from time to time. I leave the error below.