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    Not getting DHCP lease from Netgear LB1120 LTE Modem Bridged

    Routing and Multi WAN
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    • M
      mrn
      last edited by

      I'm attempting to use the LB1120 to provide backup WAN access.

      I am looking to pass through the WAN IP via bridge mode to the pfSense router.

      It's configured to get a DHCP address but the LB1120 is not providing one.

      If I connect a laptop to the modem, even through pass-through, the laptop is able to get a dhcp lease and a public ip. pfSense is not able to receive one.

      Here's the associated log for this issue:

      Mar 23 21:42:27	dhclient	51291	No DHCPOFFERS received.
      Mar 23 21:42:17	dhclient	51291	DHCPDISCOVER on igb3 to 255.255.255.255 port 67 interval 10
      Mar 23 21:42:07	dhclient	51291	DHCPDISCOVER on igb3 to 255.255.255.255 port 67 interval 10
      Mar 23 21:42:00	dhclient	51291	DHCPDISCOVER on igb3 to 255.255.255.255 port 67 interval 7
      Mar 23 21:41:47	dhclient	51291	DHCPDISCOVER on igb3 to 255.255.255.255 port 67 interval 13
      Mar 23 21:41:38	dhclient	51291	DHCPDISCOVER on igb3 to 255.255.255.255 port 67 interval 9
      Mar 23 21:41:31	dhclient	51291	DHCPDISCOVER on igb3 to 255.255.255.255 port 67 interval 7
      Mar 23 21:41:26	dhclient	51291	DHCPDISCOVER on igb3 to 255.255.255.255 port 67 interval 5
      

      Any hints for how to get this to work?

      I already tried to set this in the Options modifiers for this interface, based on some other forum posts I found elsewhere, without any luck:

      supersede subnet-mask 255.255.255.0
      
      chpalmerC 1 Reply Last reply Reply Quote 0
      • chpalmerC
        chpalmer @mrn
        last edited by

        @mrn try rebooting the modem. each time you change what you have plugged in to the modem you must reboot it due to the fact that it will lock on the first Mac address it encounters during that boot.

        Triggering snowflakes one by one..
        Intel(R) Core(TM) i5-4590T CPU @ 2.00GHz on an M400 WG box.

        M 1 Reply Last reply Reply Quote 0
        • M
          mrn @chpalmer
          last edited by mrn

          @chpalmer Thanks for the tip. I did restart when I was doing my testing. Just in case I tried to restarting again.

          I rebooted the modem and then I also rebooted pfsense.

          I tried with the special options modifier, and I also tried it without the options modifier.

          Mar 24 16:53:32	dhclient	83583	exiting.
          Mar 24 16:53:32	dhclient	83583	connection closed
          Mar 24 16:53:32	dhclient	52303	FAIL
          Mar 24 16:53:32	dhclient	83583	No working leases in persistent database - sleeping.
          Mar 24 16:53:32	dhclient	83583	No DHCPOFFERS received.
          Mar 24 16:53:25	dhclient	83583	DHCPDISCOVER on igb3 to 255.255.255.255 port 67 interval 7
          Mar 24 16:53:08	dhclient	83583	DHCPDISCOVER on igb3 to 255.255.255.255 port 67 interval 17
          Mar 24 16:52:58	dhclient	83583	DHCPDISCOVER on igb3 to 255.255.255.255 port 67 interval 10
          Mar 24 16:52:43	dhclient	83583	DHCPDISCOVER on igb3 to 255.255.255.255 port 67 interval 15
          Mar 24 16:52:36	dhclient	83583	DHCPDISCOVER on igb3 to 255.255.255.255 port 67 interval 7
          Mar 24 16:52:31	dhclient	83583	DHCPDISCOVER on igb3 to 255.255.255.255 port 67 interval 5
          Mar 24 16:52:31	dhclient	83583	igb3 link state down -> up
          Mar 24 16:52:30	dhclient	83583	send_packet: Network is down
          Mar 24 16:52:30	dhclient	83583	DHCPDISCOVER on igb3 to 255.255.255.255 port 67 interval 14
          Mar 24 16:52:16	dhclient	83583	send_packet: Network is down
          Mar 24 16:52:16	dhclient	83583	DHCPDISCOVER on igb3 to 255.255.255.255 port 67 interval 14
          Mar 24 16:52:10	dhclient	83583	send_packet: Network is down
          Mar 24 16:52:10	dhclient	83583	DHCPDISCOVER on igb3 to 255.255.255.255 port 67 interval 6
          Mar 24 16:52:08	dhclient	83583	igb3 link state up -> down
          Mar 24 16:52:07	dhclient	83583	DHCPDISCOVER on igb3 to 255.255.255.255 port 67 interval 3
          Mar 24 16:52:07	dhclient	84336	PREINIT
          Mar 24 16:51:37	dhclient	72973	exiting.
          Mar 24 16:51:37	dhclient	72973	connection closed
          Mar 24 16:51:36	dhclient	72973	igb3 link state up -> down
          

          Same issue both ways.

          M chpalmerC 2 Replies Last reply Reply Quote 0
          • M
            michmoor LAYER 8 Rebel Alliance @mrn
            last edited by

            @mrn Have you tried plugging your laptop/desktop directly into the modems ethernet (WAN) port to see if you pick up an IP address?

            Firewall: NetGate,Palo Alto-VM,Juniper SRX
            Routing: Juniper, Arista, Cisco
            Switching: Juniper, Arista, Cisco
            Wireless: Unifi, Aruba IAP
            JNCIP,CCNP Enterprise

            M 1 Reply Last reply Reply Quote 1
            • chpalmerC
              chpalmer @mrn
              last edited by

              @mrn ^^ what Michmoor said above!

              I use this same modem with Verizon and have good luck with it other than being in a poor bandwidth area.. cameras still upload to the cloud so I am happy.

              But I am in bridge mode without any extra settings.

              Triggering snowflakes one by one..
              Intel(R) Core(TM) i5-4590T CPU @ 2.00GHz on an M400 WG box.

              M 1 Reply Last reply Reply Quote 0
              • M
                mrn @michmoor
                last edited by

                @michmoor Yes it does! This is why it's driving me a but nutty.

                chpalmerC 1 Reply Last reply Reply Quote 0
                • M
                  mrn @chpalmer
                  last edited by

                  @chpalmer I wonder what I'm doing wrong...I don't even know what else to look at at this time. I guess I should post my configs soon, just in case I'm missing something obvious.

                  1 Reply Last reply Reply Quote 0
                  • chpalmerC
                    chpalmer @mrn
                    last edited by

                    @mrn can you show a screenshot of your modem interface WAN page?

                    Assuming you are absolutely not getting an IP? Not just a connectivity problem?

                    Triggering snowflakes one by one..
                    Intel(R) Core(TM) i5-4590T CPU @ 2.00GHz on an M400 WG box.

                    chpalmerC 1 Reply Last reply Reply Quote 0
                    • chpalmerC
                      chpalmer @chpalmer
                      last edited by

                      Also.. look up the MTU for the carrier you are using.. Verizon is 1400. Wont affect the DHCP but will affect traffic.

                      Triggering snowflakes one by one..
                      Intel(R) Core(TM) i5-4590T CPU @ 2.00GHz on an M400 WG box.

                      M 1 Reply Last reply Reply Quote 0
                      • M
                        mrn @chpalmer
                        last edited by

                        @chpalmer

                        Here's my pfsense interface:

                        interface.png

                        Here's my LTE modem configuration (I didn't see any other sections of importance):

                        Screenshot from 2025-03-24 23-27-49.png
                        Screenshot from 2025-03-24 23-28-09.png

                        As you can see from the following image, my laptop got the bridged IP address correctly. Oddly enough, I didn't have to reboot the LTE modem to get this IP.... I wonder if it's permanently tied to my laptop MAC address even through reboots? That doesn't seem right.

                        Screenshot from 2025-03-24 23-40-38.png

                        M 1 Reply Last reply Reply Quote 0
                        • M
                          mrn @mrn
                          last edited by

                          It's not the cable either. I just used the same cable for the router and laptop.

                          M 1 Reply Last reply Reply Quote 0
                          • M
                            michmoor LAYER 8 Rebel Alliance @mrn
                            last edited by

                            @mrn that’s a weird one. I would look into that system logs to see what’s going on (dhclient) with DHCP.

                            Firewall: NetGate,Palo Alto-VM,Juniper SRX
                            Routing: Juniper, Arista, Cisco
                            Switching: Juniper, Arista, Cisco
                            Wireless: Unifi, Aruba IAP
                            JNCIP,CCNP Enterprise

                            M 1 Reply Last reply Reply Quote 0
                            • M
                              mrn @michmoor
                              last edited by

                              @michmoor I already did that in my first post, unless you mean some other place.

                              M 1 Reply Last reply Reply Quote 0
                              • M
                                michmoor LAYER 8 Rebel Alliance @mrn
                                last edited by michmoor

                                @mrn yes i see that i apologize.
                                This doesnt seem like a pfsense related issue.
                                DHCP is 4 message types
                                Discover
                                Offer
                                Request
                                Acknowledgement

                                pfSense is sending out a broadcast looking for a dhcp server. The dhcp server (cable modem) will hear that broadcast and respond with an offer (public IP from the pool).
                                From your system log messages (assuming no filtering of the log messages), pfsense is looking for the dhcp server and its not responding.
                                As mentioned it could be a sticky mac address issue where the first record mac learned on the cable modem port is what will get the IP address and subsequent macs get nothing. If so and if rebooting the modem doesnt clear the mac then i would contact the service provider.

                                edit: Why are you hard coding a mac address in the pfsense WAN DHCP settings?

                                Firewall: NetGate,Palo Alto-VM,Juniper SRX
                                Routing: Juniper, Arista, Cisco
                                Switching: Juniper, Arista, Cisco
                                Wireless: Unifi, Aruba IAP
                                JNCIP,CCNP Enterprise

                                M 1 Reply Last reply Reply Quote 0
                                • M
                                  mrn @michmoor
                                  last edited by

                                  @michmoor

                                  The reason I hardcoded it is that I have an high availability setup. Right now the LTE modem is connected to my secondary pfsense, but I want to me able to move the connection to the primary if necessary. I know that having the same MAC address can make it a seamless transition.

                                  M 1 Reply Last reply Reply Quote 0
                                  • M
                                    mrn @mrn
                                    last edited by

                                    It won't pull an neither on bridged NOR on router mode.

                                    M 1 Reply Last reply Reply Quote 0
                                    • M
                                      mrn @mrn
                                      last edited by

                                      @mrn And yes, I have updated it to the latest firmware version.

                                      M 1 Reply Last reply Reply Quote 0
                                      • M
                                        michmoor LAYER 8 Rebel Alliance @mrn
                                        last edited by

                                        @mrn in Router mode i suspect the cable modem is giving out a DHCP address in the RFC1918 space which based on your screenshot, pfsense will ignore. Uncheck that option and test again.

                                        Firewall: NetGate,Palo Alto-VM,Juniper SRX
                                        Routing: Juniper, Arista, Cisco
                                        Switching: Juniper, Arista, Cisco
                                        Wireless: Unifi, Aruba IAP
                                        JNCIP,CCNP Enterprise

                                        M 1 Reply Last reply Reply Quote 0
                                        • M
                                          mrn @michmoor
                                          last edited by

                                          @michmoor Believe it or not, it STILL doesn't pull a DHCP lease.

                                          I'm about to return this thing and try something else.

                                          chpalmerC 2 Replies Last reply Reply Quote 0
                                          • chpalmerC
                                            chpalmer @mrn
                                            last edited by

                                            @mrn uncheck the two boxes for the reserved addresses on your WAN page.

                                            Triggering snowflakes one by one..
                                            Intel(R) Core(TM) i5-4590T CPU @ 2.00GHz on an M400 WG box.

                                            1 Reply Last reply Reply Quote 0
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