I replaced Netgear WNR3500L with Netgear R8000. I had WNR3500L's WAN port connected to TP-LINK TD-W8960N DSL modem (setup in router mode) and obtaining IP address and DNS servers from it using DHCP. I connected R8000 the same way and I have "Internet IP Address" set to "Get Dynamically from ISP" in "Internet Setup". Nevertheless R8000 does not get assigned IP address and DNS servers. Why?

> [...] I have "Internet IP Address" set to "Get Dynamically from ISP"> in "Internet Setup". [...] What about all the other Internet Setup settings? Did you tryletting the set-up wizard do what it does? > [...] Why? Who knows? With my weak psychic powers, I can't see any of the LEDindicators on any of your devices, or any of the R8000 Internet Setupsettings (save one), or the configuration of your old WNR3500L. Couldbe a bad Ethernet cable, for all I know. If you connect a computer to the TD-W8960N, does _it_ get good IPparameters? (Namely?) > [...] TD-W8960N DSL modem (setup in router mode) [...] "I connected> R8000 the same way [...] Why, exactly, are you arranging a cascade of routers, instead ofusing one router (modem and router, or modem+router and wireless accesspoint)? Cascading multiple routers can cause multiple problems (doubleNAT, for example), even when you get such an arrangement to work.

Nighthawk R8000 DHCP on WAN port not working

11 Replies

antinode
Guru
Mar 06, 2021
> [...] I have "Internet IP Address" set to "Get Dynamically from ISP"
> in "Internet Setup". [...]

   What about all the other Internet Setup settings? Did you try
letting the set-up wizard do what it does?

> [...] Why?

   Who knows? With my weak psychic powers, I can't see any of the LED
indicators on any of your devices, or any of the R8000 Internet Setup
settings (save one), or the configuration of your old WNR3500L. Could
be a bad Ethernet cable, for all I know.

   If you connect a computer to the TD-W8960N, does _it_ get good IP
parameters? (Namely?)

> [...] TD-W8960N DSL modem (setup in router mode) [...] "I connected
> R8000 the same way [...]

   Why, exactly, are you arranging a cascade of routers, instead of
using one router (modem and router, or modem+router and wireless access
point)? Cascading multiple routers can cause multiple problems (double
NAT, for example), even when you get such an arrangement to work.
- piotr_dobrogost
  Aspirant
  Mar 20, 2021
  
  > What about all the other Internet Setup settings?
  
  I am pretty sure "Internet IP Address" is the only relevant option as long as we are discussing getting IP address.
  
  > Did you try letting the set-up wizard do what it does?
  
  No as I'm used to setting these things myself and do not want any wizard to set things behind my back.
  
  > If you connect a computer to the TD-W8960N, does _it_ get good IP
  parameters? (Namely?)
  
  Good advice and I should have checked this before posting. The computer did not get ip when connected to the TD-W8960N which pointed to some problem with the TD-W8960N and not R8000.
  Originally I had the following DHCP settings on TD-W8960N:
  Start IP Address: 192.168.1.2
  End IP Address: 192.168.1.3
  and a static IP lease 192.168.1.2 set for WNR3500L.
  When I replaced WNR3500L with R8000 I changed static lease for WNR3500L (in case I connect it back someday) to 192.168.1.3 and set a static lease for R8000 to 192.168.1.2 (the previous IP address reserved for WNR3500L). Funny enough with these settings DHCP just stopped working. Extending ip range by changing "End IP Address" from 192.168.1.3 to 192.168.1.4 made DCHP work again. Really wired. It seems like implementation of DHCP in TD-W8960N is such that when the number of static leases is the same as the number of IP addressed configured by means of start/end IP range the DHCP is inactive. In other words it seems like the list of static leases counts toward the limit of the number of IP addresses configured by means of start/end IP range.
  
  Now I am curious how this looks like in other routers and if the behaviour of TD-W8960N is the norm or the exception?
  
  > Why, exactly, are you arranging a cascade of routers, instead of
  using one router (modem and router, or modem+router and wireless access
  point)? Cascading multiple routers can cause multiple problems (double
  NAT, for example), even when you get such an arrangement to work.
  The only reason for this setup is that I did not like not being able to reach modem (web UI) from LAN when I had modem bridged with the rourter.
  
  Thank You antinode for helping me with this and I am sorry for getting back so late.
  - piotr_dobrogost
    Aspirant
    Mar 22, 2021
    piotr_dobrogost wrote:
    
    > Why, exactly, are you arranging a cascade of routers, instead of
    using one router (modem and router, or modem+router and wireless access
    point)? Cascading multiple routers can cause multiple problems (double
    NAT, for example), even when you get such an arrangement to work.
    The only reason for this setup is that I did not like not being able to reach modem (web UI) from LAN when I had modem bridged with the rourter.
    Hmm, according to https://superuser.com/a/993785/664 answer to the question "How do I access my modem's GUI when it's in bridged mode?" it is possible to access modem when it is in bridged mode...
ColoradoSlim
Aspirant
Mar 21, 2021
cross posting from the R7000 series, but when the WAN port doesn't pick an IP address via DHCP from the internet router it is attached to I just downloaded the firmware and did a web firmware upload. That fixed it. First I tried to factory reset it but that did NOT fix the problem.
- piotr_dobrogost
  Aspirant
  Mar 21, 2021
  ColoradoSlim wrote:
  cross posting from the R7000 series, but when the WAN port doesn't pick an IP address via DHCP from the internet router it is attached to I just downloaded the firmware and did a web firmware upload. That fixed it. First I tried to factory reset it but that did NOT fix the problem.
  Thanks for sharing this info here.
  However as I described in my previous post even computer connected to the "internet router" (in place of R8000) was not getting IP address which demonstrated that the problem was on the sending side ("internet router") and not on the receiveing side (R8000 or temporarily connected computer).

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Nighthawk R8000 DHCP on WAN port not working