I have many nodejs proxies running behind nginx, it has worked fine for years with 1 annoying exception.

When the nodejs process is restarted, the client receives a 502 error, which is OK, however nginx appears to continue refusing the connection for exactly 30 seconds, and then the connection is restored.

I need to reduce this down to a few seconds, I have seen other posts about increasing timeouts to overcome intermittent gateway errors, however this is different.

I have tried enabling keep-alive with:

  proxy_http_version 1.1;
  proxy_set_header Connection "";

But that has no effect.

Does anyone know which parameter is controlling this 30 second timeout ?