DHCP Mode with Guest Wifi

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Andrew

• August 06, 2020 16:02

I recently got a new router and set it up with DHCP mode since Simple mode isn't compatible with the model I got (TP-Link AC4000). All of that works fine, but when I try to use the guest network, the devices cannot grab an IP. I assume this is because the router is set up to be a DHCP server and hand out addresses. Does Firewalla not hand out addresses for the Guest Network? Is the Guest network just not usable in DHCP mode?

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  Firewalla

  • August 06, 2020 16:48

  In this case, very likely the Firewalla can't see the DHCP requests from the guest network inside the box.   In theory, TP-link (and a few other routers) should completely isolate the guest network, even if the main router services like DHCP is off, that network's DHCP should be up ...  

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  Lyle Cooper

  • September 25, 2020 10:36

  Hi, I have a D-link router. I have a guest network enabled, as well as a repeater to extend my coverage.

  Will DHCP mode allow me to monitor devices on the guest network? *(currently my guest network is not visible to the Firewalla)

   

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  Firewalla

  • September 25, 2020 17:01

  Guest networks that comes with your router can not be seen by any device outside;  

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  Lyle Cooper

  • September 29, 2020 11:26

  I want to confirm, the FireWalla will not be able to view devices on the guest network, even though they would get their DHCP served from the Firewalla.

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  Firewalla

  • September 29, 2020 17:25

  If firewalla is issuing the IP addresses, then firewalla should be able to see these devices.  Can you give it a try?

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  Robby

  • April 16, 2021 11:31

  I have the same issue with my new TP-link AX20 and my Blue (in DHCP mode) in that devices can only connect to the guest network if DHCP is enabled on AX20. I assume that they would be able to connect if they locally set a static IP.

  Is there any way around this issue? I had the same issue with my previous Vodafone router but it's only just become known to me because no guests have been visiting for over a year. It seems to me that if a Firewalla Red/Blue is likely to render the guest WIFI almost useless then it should be clearly detailed somewhere

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  Firewalla

  • April 16, 2021 16:43

  How this works depends on the guest mode implementation.  For example, for some routers, even if you disable the DHCP server on the router, the hidden guest network will still work.   Some routers when you disable DHCP, it means to disable the DHCP service for everything ... 

  In your case, if you don't mind trying this, I have seen this work on some routers.

  1. Turn DHCP server back on your router.

  2. Then start to give the DHCP range on the TPLink to limit the range, for example, 192.168.1.2 - 192.168.1.2

  3. step 2 is essentially like turning off DHCP server.  This way, the router can still give out IP to your guest network.

  The steps above are documented here https://help.firewalla.com/hc/en-us/articles/360009259414

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  Robby

  • April 17, 2021 06:10

  Thanks for the info. I've given those steps a go and like you say it's 'essentially like turning off DHCP server' and so I don't see how it could work. It doesn't for me (tp-lnk AX20 + Blue). The static IP address is  assigned to the Firewalla (coincidentally also 192.168.1.2 for me) but then there are obviously no dynamic IPs left for the guest network to assign and so nothing can connect to the guest WIFI. Am I misunderstanding the solution?

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  Firewalla

  • April 17, 2021 06:15

  The guest network will pick up a different IP range that's different than your main network.  (In theory, most router does this ...). Since you are already in DHCP mode, firewalla will handle the main network DHCP assignment.

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  Robby

  • April 17, 2021 07:02

  hmmm I still don't understand. This is my current config:

  1. Router IP is 192.168.1.1

  2. Router DHCP is enabled with a range 192.168.1.2 -> 192.168.1.2

  3. Router has a static IP set for the Blue which is 192.168.1.2

  4. The Blue is in DHCP mode. Its overlay network IP is 192.168.144.1 and the overlay network DHCP range is 192.168.144.50 -> 251

  So with that config no WIFI devices can join the guest network. If I extend the router's DHCP range then devices can join the guest WIFI, but then also but then also devices that join the main WIFI are assigned IPs by the router (IPs within the router's range) rather than by the Blue

   

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  Robby

  • April 21, 2021 11:16

  Hi Guys, Any more thoughts regarding this?

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  Firewalla

  • April 21, 2021 16:39

  When devices can join the guest network, what IP addresses are they getting? is it the same as 192.168.1.x?  or it is something else?  Usually, we know the guest network is numbered differently from the main network. 

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  Robby

  • April 26, 2021 15:23

  If the DHCP server is enabled on the router then all devices joining either the main or guest WIFI are assigned an IP by the router, for example 192.168.1.x. It appears that if the router DHCP server is enabled then it wins the race to assign an IP address (beating the Blue).

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