Interface on Half-Duplex without any reason?

  • Hello,

    i am trying to configure our new ISP (Colt) on our pfsense appliance (scope-7).

    Our ISP told us to configure the WAN interface for 100mbit full duplex.
    The autodetect functions sets it to 100mbit half duplex and forcing full duplex has no effect at all.

    We do not get any packets back from our ISP and i guess it has something to do with the wrong duplex mode.

    Any ideas why that happens?


  • If it negotiated that then there is a problem.  Bad cable, jack or device.

    Ethernet 101.

  • Or the device just doesn't support full duplex (in the case of a hub, for example). Switches are full duplex, though, so if you have a hub between your ISP modem and your pfSense box, replace it.

  • If you are using the APU based unit, that is likely your problem. The realtek nics won't auto-negotiate with some hardware and get stuck in half-duplex. I've seen it mostly with cheap media converters on Fiber installs. Our solution was to swap the hardware to something with Intel nics.

  • Have you tried setting interface to "default" rather than "auto-detect"?  I've seen strange behavior when set to auto-detect with some adapters.

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