DHCP won't assign one device.

  • Hi All,

    Been using pfSense for a while now and this forum has helped me along my journey!

    I'm a little lost now though as this issue doesn't make any sense to me.

    I have one device which is an UniFi US-8-60W that won't get an address from DHCP, I have multiple VLAN's setup with their own DHCP and no matter what VLAN I put it on DHCP won't hand it an address.

    I've checked the UniFi switch on a test network with DHCP from a Draytek router and it gets an address just fine.

    I've restarted DHCP even to the point of restarting pfSense, checked logs but I'm either not looking in the right place or there is nothing to see log wise.
    Any other device on these networks picks up an address just fine.

    If the UniFi kit wasn't so alien to static IP's I'd go that way over this one little switch but my usual method is DHCP reservations for my network kit so I'd like to continue that.

    Any ideas would be welcome as I'm all out of ideas and I think Google is as well.

  • LAYER 8 Global Moderator

    Well does the pfsense log show discover from the device for dhcp? Do a sniff - if you do not see a discover then no pfsense will never give it an IP.

    if it sees the discover and your not getting an IP then the reason why should be in the log, or for sure you can tell from the sniff. Pfsense sees the discover, but doesn't send the offer? Or it sends the offer and the client doesn't get it - doesn't like it, etc.

  • Try to somehow do a complete “release” on device. pfSense won’t respond to a request from a device that has a stale IP, for some reason.

    The DHCP Server log will indicate it.


  • LAYER 8 Global Moderator

    Don't assume that @mikehsr - lets get the details of your post before you go assuming your issue is what is happening with this poster.

  • @johnpoz

    pfSense sees the offer and posts something in the log different from others.

    I’ll have to setup the problem again and get back to you.



  • LAYER 8 Global Moderator

    pfsense would not be seeing an offer, it would be sending it..

  • Sorry! It sees the request.

  • LAYER 8 Global Moderator

    Well if the dhcpd sees a request and sends an offer - then the client should accept it, and send the ack...

    A sniff of your problem will show you exactly what is going on, once you open the dhcp traffic in wireshark you will be able to see all the details of the request, the offer, etc..

    Seeing the traffic will be very helpful in figure what is wrong. The server would send offer, then client would send the request, then server would send back ack saying yup you can have it.

    There is some differences in the handshake when its a renew vs a discover, etc.

  • Many thanks for the replies!

    I've got wireshark running on that subnet and never see a DHCP request from the switch.

    If I bounce one of my Linux boxes I see the discover and request in wireshark.

    Think I'm even more confused now as this switch works on another DHCP like my Draytek box and I used the tool from the following link on a laptop and that gave the switch an address.

  • Me again, after backing the switch firmware right down to 3.8.6 the switch asks for an address and gets one from pfSense.

    So I think the issue is with the switch, no idea why it an address from another DHCP but there you go.

    Thanks all again.