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DHCP LAN: How to release/renew on the LAN, not the WAN

wastenot
Tutor

DHCP LAN: How to release/renew on the LAN, not the WAN

I am aware of https://community.netgear.com/t5/Nighthawk-WiFi-Routers/How-do-I-release-and-renew-the-IP-address-on... is the way to release/renew the DHCP on the WAN. But my router is also a DHCP server for LAN-connected devices. How do I release/renew those devices?

 

Model: R7000|Nighthawk AC1900 Dual Band WiFi Router
Message 1 of 4
antinode
Guru

Re: DHCP LAN: How to release/renew on the LAN, not the WAN

> [...] How do I release/renew those devices?

   Why?

   Normally, you might do it from the (each) client, if there were some
actual reason to do it.  From the router, rebooting the router might be
the easy way.  But why?

Message 2 of 4
wastenot
Tutor

bgoodr@gmail.com

I need to find a way to release and renew without rebooting the router because the router takes way too long to come back up.

The reason I want to do this is that I have statically assigned IP addresses for all of my devices and I want to try to find all of the other devices that are not statically a assigned so that I can determine if there are any devices that I missed.
Message 3 of 4
antinode
Guru

Re: bgoodr@gmail.com

> The reason I want to do this is that I have statically assigned IP
> addresses for all of my devices [...]

   I assume that you mean _reserved_ IP addresses.  "Static" normally
means "not obtained by DHCP".  ("D" for "Dynamic", the opposite of
"Static".)

> [...]  and I want to try to find all of the
> other devices that are not statically a assigned so that I can determine
> if there are any devices that I missed.

   The easy way to do that would be to use reserved addresses which are
outside the DHCP pool.  Then, you'd know that anything from the pool was
not a reserved address.

   Around here, for example (D7000, V1.0.1.50_1.0.1), the (small) pool
(ADVANCED > Setup > LAN Setup : Use Router as DHCP Server) is:

      Single/Start IP Address         10.0.0.224
      Finish IP Address               10.0.0.239

The Address Reservation list (same page) includes:

       9  10.0.0.120  orvibo-00  AC:CF:23:48:ED:12
      10  10.0.0.121  orvibo-01  AC:CF:23:9C:B2:14

The BASIC > Attached Devices : Wireless Devices list includes:

      Allowed  ORVIBO-00        10.0.0.120  AC:CF:23:48:ED:12  Wireless
      Allowed  ORVIBO-01        10.0.0.121  AC:CF:23:9C:B2:14  Wireless
      Allowed  ROKU 2 XD - 779  10.0.0.226  B8:3E:59:26:A1:09  Wireless

   In this case, the Orvibo S20 sockets get those non-pool addresses
from the routrer's DHCP server, but the Roku box gets a non-reserved
address from the pool.  (I can control the Orvibo sockets more easily if
I know their IP Addresses, but no one cares where the Roku box is.)

   Perhaps you thought that the DHCP server provided addresses only from
the pool.  Nope.  I also have some devices with static addresses,
assigned manually by me, not using DHCP.  Here's one (a Mac Pro):

      Allowed  PRO3             10.0.0.79   00:1F:5B:30:C0:7C  Wired

   My DHCP pool is so small (239 + 1 - 224 = 16) precisely because very
few devices get addresses from the DHCP pool.  Many are static (when
that's easy to configure), and most of the rest have reserved addresses
(when a static address would be inconvenient to configure).  Only the
left-overs get an address from the pool.  At the moment, the Roku box
seems to be the only one.

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