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pfsense doesn't acquire wan ip

jasonalexanderlh Posts: 1 Newcomer

I have a pfsense box that I've setup and ready for wan/internet access. When I connect the wan interface directly to the modem, pfsense will not get an IP address. But it will get an IP address when connecting to the spectrum wireless router. This is residential and should be getting a DHCP IP.


pfsense wan works and gets an IP when connecting to the spectrum wireless router which is connected to the spectrum et2251 modem.

pfsense wan does not get an IP when connecting directly to the et2251 modem

Are there setting changes I need to make to the pfsense wan interface to connect with the et2251 modem, i.e: MTU, CIDR block



  • Paul_B
    Paul_B Posts: 577 Spectrum Employee

    Good morning -

    There would be no settings directly on the modem that can be modified. It should work without issue provided that the pfsense box is setup for DHCP. When you switch the connection between the Spectrum router and directly to the modem, are you reboot both the pfsense box and the modem to allow everything to refresh and allow the modem to assign an IP to it?

    That is all that should really need to happen for the pfsense box to get an IP address.


  • Mr_SoCal
    Mr_SoCal Posts: 3 Spectator

    Every time you attach a device with a different MAC than before you have to reboot the modem to trigger DHCP exchange and acquire the (possibly new) IP address. If you want to avoid the reboot I think pfSense lets you spoof the MAC address but that might not work.

    I have a different but related problem. For many years after rebooting the modem my router would get both DHCPv4 and DHCPv6 replies. Since one week or so it only receives DHCPv4 info. The DHCPv6 never arrives so the v6 interface on my router just sits there with no relevant info (no IPv6 address and not gateway address) Any recommendations what I should do? The phone tech person(s) just told me that they cannot help me beyond recommending the modem reboot.

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