When both pfSense and cable modem are rebooted, cannot obtain DHCP lease



  • I'm having a very strange problem and I've done lots of testing and searched high and low for an answer. I'm hoping someone else has gone through this madness and can shed some light on it.

    Charter Communications is my ISP. I have a cable modem that connects to pfSense WAN. Once I obtain a DHCP lease, everything runs smoothly. Even renewals work without flaw. The only thing that breaks is if I reboot both the cable modem and the pfSense server at the same time. I've tested many combinations of reboots and only this combo breaks. Allow me to give a clear outline of the scenarios. Each scenario assumes that immediately prior pfSense had obtained a valid DHCP lease and Internet access was working.

    • Reboot only pfSense. DHCP lease is obtained properly on boot.
    • Unplug the ethernet cable. Reboot only the cable modem. Release and renew the lease in pfSense. DHCP lease is obtained properly.
    • Shutdown pfSense. Disconnect the ethernet cable from the modem. Reboot the modem.  Allow the modem to fully boot and lock on to the Charter network. Plug in the ethernet cable. Start the pfSense server. Cannot obtain DHCP lease on boot, or with subsequent release and renew.

    Any ideas why this last scenario fails? On top of it all, because the DHCP requests are not answered by Charter, the rapid requests from pfSense get me on a temporary blacklist and I have to wait 1-2 hours to request a new DHCP lease and have it successfully filled. (I'm guessing I'm getting on a blacklist temporarily based on the required wait time and after talking with a former cable company engineer)

    I want to know that if a power failure occurs, or when I need to power everything down to move/re-arrange it, I can quickly restore Internet access. Waiting 1-2 hours is not that nice.

    Thanks for your help.



  • Did you ever figure what was causing this. I have the same problem. Charter Internet cable modem. On a power failure no DCHP from cable modem. Not sure about the blacklist thing as it takes me more than 2 hours to get to the device. When I do I power down cable modem and firewall. Wait for modem to boot up and connect to network then power up firewall. It gets DHCP address.