DHCP issue (or at least I think so)

  • Hello all,
    I have quite a strange issue within out corporate network. We are using pfsense 2.1-RELEASE (amd 64) as a router/ DHCP/ DNS. The problem occurred two days ago once we replaced our old wifi access points (netgear home routers configured as AP) with Cisco wifi controller 2500 and three cisco 1600 wifi AP. Since then no iphone connected to the wifi network receives IP address from the DHCP server. I checked the logs on the DHCP server and I can identify the requests from iphone devices and the responses that the DHCP server sends back:

    dhcpd: DHCPOFFER on to 0c:73:1a:79:22:33 (IPhone) via
    dhcpd: DHCPDISCOVER from 0c:73:1a:79:22:33 (IPhone) via

    but then when I check the IP address of this iphone it is 169.X.X.X. This problem occurred on iOS 6.1.3, 7.0 and 7.2 (around 7 devices - iphone 4S and  5), according to my colleagues they can use their iphones to connect to other wifi networks without any problems. If I set static IP address (in the iphone settings) they can use the network resources without problems.

    In addition all other devices - laptop/ ipad/ imac/ balckberry/ android smartphones are connecting and obtaining IP address using the wifi network without any problems.

    p.s. I have 100 IP addresses dedicated for the DHCP pool and we have up to 50 wifi devices connected to our wifi network.

    Any suggestions are welcomed.

  • What kind of hardware does the pfSense 2.1 run on (specifically the lan controller)? Although not the same problem as you're describing, I have a Windows 7 machine that occasionally drops out of the network due to not being able to renew its DHCP lease. I could see the DISCOVER/OFFER sequence (but not the ACK) when it happened in the DHCP logs on the pfSense unit. Since I haven't had this problem with my previous router (Netgear), I suspected that it might have something to do with the pfSense box I am running on. In my case, the pfSense box has Realtek 8111 chip (and so does the Windows 7 box). At some point, I need to track it down and figure out why it can renew DHCP lease. Not that I think it might be relevant, however, there are a couple of settings in the Advanced Networking tab (System->Advanced->Networking) such as LRO, TSO, and hardware checksum. You could try if enabling/disabling any would make a difference (might need to reboot after modifying the settings). Good luck.

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