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tcp write failed - all of a sudden and without reason?

j0ka
2024-07-20
2024-07-20
  • j0ka

    j0ka - 2024-07-20

    iperf used to work well for weeks (using Win 10 connected WiFi with AVM Fritz!Box 7590 router), but all of sudden it stopped working two days ago, for no apparent reason.

    The problem is that iperf does not give me any hint on what could be wrong. I call it with the following command:

    "iperf-2.2.n-win64.exe" -c ###.###.###.### -p 4711
    

    And here's the output:

    Client connecting to ###.###.###.###, TCP port 4711
    TCP window size: 64.0 KByte (default)
    ------------------------------------------------------------
    [  1] local ###.###.###.### port 49854 connected with ###.###.###.### port 4711
    [  1] tcp write failed
    [ ID] Interval       Transfer     Bandwidth
    [  1] 0.00-6.20 sec  11.7 GBytes  16.2 Gbits/sec
    

    So I tried some things on my own: restarted router, computer, checked firewall, virus scanner, router settings ... but without success.

    How can I get more information about the reason for the tcp write fail?

    (I wonder that iperf does not output any error details, such as e.g. a timeout or something like that. Instead, it seems to continue and outputs ridiculous high transfer rates whic are far beyond the physical possibilities of my system. Is that intended behaviour or a bug?)

     
    • Robert McMahon

      Robert McMahon - 2024-07-20

      Can you file a ticket for this? Iperf should pr int the error code but it currently doesn't.

       

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