Thank you.
As i wrote in reply to B. R., i'm trying to catch an 408 response from an upstream server, and turn it into a 302 redirect.
Since the upstream is the one answering with 408, i cannot control its logic by tweaking Nginx configuration.

In my scenario, the client is "fast enough", as Nginx accepts its request and sends a request to the upstream.
So theoretically Ngnix should consider the client "fast enough" to answer to it.

So i still believe it should be valid to intercept this 408 response from upstream and turn in into a different response toward the client (302 in my case).

Still, i accept the fact that my logic might be wrong, and i'm open to hear alternative reasoning.

Thanks,
Shmulik