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We have a Apache/Tomcat server. Recently a client from UK report that he can't connect to our server. We captured the fiddler log, and found it received 504 error, and the statistics like below: Fiddler 504 Error

Request Count:   1
Bytes Sent:      1,508      (headers:1,508; body:0)
Bytes Received:  717        (headers:205; body:512)

ACTUAL PERFORMANCE

This traffic was captured on 2020/5/29.


NOTE: This request was retried after a Receive operation failed.

ClientConnected:    19:06:21.821
ClientBeginRequest: 19:06:22.504
GotRequestHeaders:  19:06:22.504
ClientDoneRequest:  19:06:22.504
Determine Gateway:  0ms
DNS Lookup:         0ms
TCP/IP Connect:     234ms
HTTPS Handshake:    460ms
ServerConnected:        19:06:22.970
FiddlerBeginRequest:    19:06:23.430
ServerGotRequest:       19:06:23.431
ServerBeginResponse:    19:06:22.735
GotResponseHeaders:     19:06:22.735
ServerDoneResponse:     19:06:23.661
ClientBeginResponse:    19:06:23.661
ClientDoneResponse:     19:06:23.661

    Overall Elapsed:    0:00:01.157

RESPONSE BYTES (by Content-Type)

--------------
text/html: 512

~headers~: 205

We never meet this problem in the internal network, and the US clients didn't report this issue. While this client could connect successfully to some other server in our company(The same domain, but different subdomain).

This problem really puzzled me. I have check the client system clock correct, the wininet setting has enabled TLS1.0 TLS1.1 TLS1.2. What else could we do to check this kind of problem ? The client's system settings, the network or the server logs ?

Thanks,

Frank

Frank
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  • By the way we noticed the client side log report below errors : "GatewayTimeout" when connect to our server. When using the Firefox to connect to our server, it has serveral times "Performing a TLS handshake to ..." messages. – Frank Jun 01 '20 at 12:50
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    If the client managed to receive HTTP status 504 from your server, there was certainly no network connection problem at all, just an error generated by your server, for whatever reason that may have been. – user207421 Jun 01 '20 at 13:40
  • @user207421 Thanks. But how to figure out what the problem is. It's a little weird because we have thousands of clients from UK and US, only this client report the error. And we have the server for years, never experienced this problem in our internal network even when the server is at peak time. – Frank Jun 01 '20 at 14:52
  • See the attached fiddler log. There is a warning message : NOTE: This request was retried after a Receive operation failed. And the "ServerBeginResponse" is a little earlier than "ServerGotRequest". What does this mean? – Frank Jun 01 '20 at 14:55
  • And the "TCP/IP Connect" "HTTPS Handshake" time also seems a bit longer than normal ? – Frank Jun 01 '20 at 15:01
  • Have you considered lookup up HTTP status 504? It means 'gateway timeout', i.e. timeout on some upstream service. Consult your Tomcat logs, and those the upstream service. All these packet sniffs and fiddler logs are barking up the wrong tree completely, as is the title of your question. – user207421 Jun 02 '20 at 03:36

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