WAN DHCP goes offline



  • Related to pfSense 2.2, Dec 16 snapshot

    Yesterday I assembled new router with following HW:

    Intel NUC DCCP847DYE with built-in Intel® 82579V lan
    4Gb RAM
    Netgear GS105E-100NAS, VLAN set up

    On the switch:
    Port 1: Router connected to the switch via Trunk
    Port 2: Cable modem, DCM475, WAN-DHCP on em0_vlan2
    Port 3: DSL Modem, PPPoE on em_vlan3
    Port 4: em0_vlan10 unused
    Port 5: LAN on em0_vlan10

    Cable & DSL go in failover group,
    Cable (DHCP) foes as Tier 1,
    DSL as Tier 2.

    Used this setup for a long time on different PC based setup (Celeron 1037 + 4 port Intel LAN, no VLAN)

    WANS are probed with 8.8.8.8 and 8.8.4.4

    When I started, had to restart my Cable modem so it's gateway goes online. It was fine at the evening, though next morning Cable WAN was offline.
    Setup was working fine though, failed over to DSL line (Tier 2)

    Restart of Cable modem didn't help. Had to switch back to old setup, pfSense 2.1.5, 4-port lan

    Yesterday I set up a pfSense 2.1.5 with the same config file on the above mentioned, new hardware (Intel NUC + VLAN GS105E-100NAS). Works fine, no issues at all as it was on previous hardware

    Can provide exact config file



  • Config file probably wouldn't help since all that works fine in general. Power cycling your cable modem after changing devices is required in most all circumstances for your cable modem to forget the old hardware's MAC and pick up the new.

    Need to figure out why the WAN dropped. Did you have the old system completely unplugged? What did Status>Interfaces show for WAN when it was down? What relevant logs were in the system logs at the time (Status>System logs, System tab)? Also DHCP tab there, what did dhclient log?



  • Since you have changed the hardware around, most notably, the switch, I would look there first. Cable modems, while providing great connectivity, are dumb devices. Remember, they lease an address to the first address they see. These difficulties arise when wanting to go the single NIC route and use VLANS with a cable modem. It does work however, you just have to ensure your switch port for the cable modem is configured properly. Below is how I had to configure mine on a Cisco switch to work, only difference is my WAN Cable is VLAN 104.

    switchport access vlan 104
    switchport mode access
    no cdp enable
    spanning-tree portfast
    spanning-tree bpdufilter enable



  • Didn't see where the switch was changed, but if that's the case, especially given it's a managed switch, there can be issues introduced by your cable modem from seeing traffic the switch is sending and treating its MAC as the device authorized to use the Internet. I had a cable modem that'd see STP, LACP, CDP or similar traffic from a directly-connected managed switch and pick that MAC as the one it'd let out. Even if the switch wasn't changed, it could just happen to have hit that circumstance by chance where it didn't before.


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