Problem with DHCP server from macOS after getting new router from operator



  • Hello guys,

    I am seeing some odd behaviours, in two new different routers with DHCP servers hosted in servers, in a small office.

    After my new operator changed my old fiber router from other operator for a new one(gr241ag), I lose the hability to use my server DHCP that I had, with this router with his DHCP disabled. With my server DHCP ON, new devices where unable to receive IPs.

    Then I tried a new router, a Huawei B315, and same result, with just one DHCP server of that server, having that Huawei with his DHCP server disabled, I had the same result.

    In all cases I was able to ping from my server to my router, without problem. Both where in the same subnet.

    Then I used my pfsense VM that I have for OpenVPN, and tried to config a DHCP server there, and with that Huawei, I was able to give IPs only to wired users, with smartphones android, I tried with 2 and there was no DHCP server available. There is no configurations just for wire and wifi in this device, it is a simple home router.

    This network had several non-smart switchs, connected just to one router.

    My question is, if you know what can be happening.


  • LAYER 8 Global Moderator

    Huh?  Read this like a 3 times..  Not sure what your asking.

    You can run dhcp on anything.  A linux box, a windows box, pfsense, etc. etc..  As long as the devices are on the same L2 then the dhcp server would see the discover and offer an IP.  If your having problems with devices getting an IP your going to have to trouble shoot why.

    But changing the edge router would have zero to do with dhcp on your network - if the dhcp server is disabled on the device you swapped in, etc.



  • @johnpoz:

    Huh?  Read this like a 3 times..  Not sure what your asking.

    You can run dhcp on anything.  A linux box, a windows box, pfsense, etc. etc..  As long as the devices are on the same L2 then the dhcp server would see the discover and offer an IP.  If your having problems with devices getting an IP your going to have to trouble shoot why.

    But changing the edge router would have zero to do with dhcp on your network - if the dhcp server is disabled on the device you swapped in, etc.

    I have configurate several DHCP servers and in all cases was has you said, but for the first time I am seeing this issues with those two routers, where just with one DHCP server not hosted in router, new devices cannot get new IPs and with pfsense DHCP server at least with that Huawei, just wired connections can get new IPs.

    I admit that I didn't had time to test with GR241AG router(that router had a firmware problem, I have already contact support for that device) like I have done with Huawei B315.

    At least with Huawei B315 I notice that I was not the only one with that issue, but cannot figure out why, with Androids: https://www.raspberrypi.org/forums/viewtopic.php?f=36&t=182957


  • LAYER 8 Global Moderator

    If your using pfsense, why would you be running dhcp on some isp gateway/router?  All of your devices would be behind pfsense and some isp device at best would be bridge, and pfsense would get public on its wan.  And worse it would be a double nat and pfsense would get IP in the dmz host network of the device which pfsense should be static..

    I don't really see why any devices would be using dhcp off this isp device at your edge if your wanting to use pfsense.  If devices connected to this are having problems - this really has ZERO to do with pfsense.

    And while this is the general area - you would be better off in the forums of whatever device it is your using or having a problem with getting dhcp from it.

    Simple sniff from should show you the whole process discover, offer, request, ack… If you want to post up a sniff we can take a look.. Is the isp device not sending a offer, is it not seeing the discover?  Is it not answering the request.. etc. etc..

    Unless your doing a dhcp relay on pfsense, pfsense really has nothing to do with a dhcp server and a client on an L2..



  • @johnpoz:

    If your using pfsense, why would you be running dhcp on some isp gateway/router?  All of your devices would be behind pfsense and some isp device at best would be bridge, and pfsense would get public on its wan.  And worse it would be a double nat and pfsense would get IP in the dmz host network of the device which pfsense should be static..

    Wait, this pfsense is running in a VM (Virtual Machine), and DCHP server from pfsense was just used for test purposes.

    @johnpoz:

    I don't really see why any devices would be using dhcp off this isp device at your edge if your wanting to use pfsense.  If devices connected to this are having problems - this really has ZERO to do with pfsense.

    And while this is the general area - you would be better off in the forums of whatever device it is your using or having a problem with getting dhcp from it.

    I know, but was especting that someone here would have already encounter the same situation with other devices, thats why I have post it in General Area.

    @johnpoz:

    Simple sniff from should show you the whole process discover, offer, request, ack… If you want to post up a sniff we can take a look.. Is the isp device not sending a offer, is it not seeing the discover?  Is it not answering the request.. etc. etc..

    Unless your doing a dhcp relay on pfsense, pfsense really has nothing to do with a dhcp server and a client on an L2..

    I will follow your first advice to went in foruns dedicated to those devices(I still have to search), and if I doesnt found a solution, I will have to do it, and will do it.

    Thanks for help johnpoz!


  • LAYER 8 Global Moderator

    Users are here because they use pfsense - even in the general area.. So while yes there is a huge amount of networking knowledge here.. Most here don't give 2 shits in helping someone with some other devices problems.

    If you had a general question of dhcp or networking in general - happy to discuss.. But more than likely your not going to find many people willing to help you solve some other devices dhcp issues.

    As to what issues you had with pfsense when you were running it as VM for your dhcp server - more than likely this was related to something else in your network..  I have run pfsense as vm for years and years - zero issues with dhcp on it.  I still have a pfsense vm running as a downstream router in my network, and it has zero issues with dhcp to other vms and or wired/wireless devices in the network.

    dhcp is really easy to troubleshoot overall.  Most problem stem from users running multiple dhcp in the same L2, or just in general not even understanding what is meant by L2 or L3 networks.

    If you want to post up something we can actually work with, like a sniff of the dhcp traffic be happy to discuss that here in the general section because its just general networking at the basic level talking about dhcp protocol.


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