IP address conflict on new install despite changing it?

  • I have an existing pfsense router on that's working great. I had to set up another one for another location so I built the box, did a fresh install and before connecting any ethernet cables I set the interface IP to and chose not to enable DHCP.

    I then connected the cable, pinged a couple of hosts to make sure it was working then before I sat back down at my desk I was getting reports of network outages. When I started pinging google from my desktop I was receiving destination unreachable replies from

    A quick netstat -r -n showed me that was still the default route.

    What did I do wrong? What is it that causes that to happen and how can I have two pfsense boxes on the same network segment without them fighting?

    Thank you.

  • Hi,

    Well, ... good question. Don't know what went wrong, you didn't mention it.

    It's possible to assign a IP like to the LAN interface, so you can hook up this second pfSense box to an already existing LAN network. And yes, the DCHP server should be stopped - not running on LAN.
    In this case the WAN interface isn't connected, so you'll be having troubles installing packages and upgrade pfSense.

    I advise you to setup your LAN to, for example, - start DHCP on your LAN.
    Hook up the WAN interface to your existing LAN, and your desktop to the new pfSense LAN interface.

  • Thank you for the reply. The fault I'm more interested in is how changing the interface IP appeared to somehow NOT change the interface IP.

    I checked and despite ifconfig reporting that igb.1 was, the box was merrily responding to arp requests for The switch dutifully recorded this otherwise I might never have noticed.

    It's as if there was some lag between setting the new interface IP and whatever responds to arp requests agreeing on the change. It's far too low level for me to know what to look at.

    I know now to give the box a reboot after a change like that before I put it on a live network. Could it be the network card? Some sort of hardware offload that's being stupid? Is it something the pfsense interface should warn about or is it so absurdly specific to my setup that it's not worth it?

  • Just after I got an IP conflict error message in my system, I found my Epson Printer In Error State which it was connected with. It has stopped me from using the printer. How will I be able to stop the occurrence of such error now?

  • @slightlybeige said in IP address conflict on new install despite changing it?:

    The fault I'm more interested in is how changing the interface IP appeared to somehow NOT change the interface IP.

    Connecting to an Interface and changing the IP is time critical. I can't test it right, now, but I guess you wind up having a big green Apply button. Ones hitting that, there will be a message that states that pfSense changes LAN settings, and a browser redirect should activate in "20 seconds". After the delay, the GUI should work on
    If you connected your new pfSense to early, some of your network devices might have 'sniffed' that another "" device was present on the network, and things go haywire.

    Btw : when starting up a new pfSense, I always activate the console access. Serial if possible, if not keyboard/VGA and by SSH also. Maintenance related to the GUI itself, IP changing, etc, I don't use the browser that, I use the console.

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