We have LB 440 where HTTP(S) services are configured to use "Default failure response" as "Last Resort Action".
According to the docs it's supposed to return "503 default error page" response in case if all back-end servers are down/unavailable.
But it returns "Connection Reset" with empty response. This is the response using curl:
* Recv failure: Connection was reset
* Curl_http_done: called premature == 1
* Closing connection 0