This is horrible and gets worse with every update. I have iPhone8max, 2 of them, 5th gen ipad, Apple watch5, 2 of them. ALL OF THEM keep switching to 169 ipad dresses even though my 192 network is very strong
iPad, iOS 11
As all devices are similarly affected, your description suggests that something untoward is occurring with the DHCP Server on your network - and that it here that you will need to focus your attention. “169” IP Addresses are automatically assigned by connected devices when they request an IP Address via DHCP - but do not receive a response from the server.
For domestic WiFi networks, DHCP services will usually be provided by your Internet Router - which, quite often, also provides your WiFi connection.
Very often issues with a WiFi Router can be simply resolved by restarting the router. To do so, just disconnect AC power for about 30-seconds, then reconnect power and allow the router to fully restart (this may take many minutes).
As all devices are similarly affected, your description suggests that something untoward is occurring with the DHCP Server on your network - and that it here that you will need to focus your attention. “169” IP Addresses are automatically assigned by connected devices when they request an IP Address via DHCP - but do not receive a response from the server.
For domestic WiFi networks, DHCP services will usually be provided by your Internet Router - which, quite often, also provides your WiFi connection.
Very often issues with a WiFi Router can be simply resolved by restarting the router. To do so, just disconnect AC power for about 30-seconds, then reconnect power and allow the router to fully restart (this may take many minutes).
Okay… so you have four fixed IP Addresses, one of which will assigned to your Router - leaving three others for fixed devices. To all intents and purposes, your entire sub-net (192.x.x.x) is essentially DHCP. Unless your Router has a hard-limit as to the number of client devices that it can support, address exhaustion shouldn’t be an issue.
The issue that you describe still suggests that the problem is DHCP related. Check your network settings on each of your Apple devices - ensuring that each device IPv4 Address is set to Automatic. Also check that DNS is also set to automatic.
Assuming that your devices are running iOS/iPadOS14, disable the Private Address option.
I clearly have no insight into the resources or discussions that have brought you to this Apple Support Community. I am, however, working the information that you have provided - and attempted to gain an understanding of your network setup/topology.
On the basis of information you have provided, it is my understanding that you have connected your AirPort Express, via an ethernet cable, to a single ethernet port of your Nighthawk Router. The AirPort Express is configured in bridge-mode - and is effectively behaving a WiFi Network Access Point for your Apple (and some other) devices - some connecting via other WiFi extenders.
Your AirPort Express and Nighthawk router are assumed to be advertising entirely different SSIDs (WiFi network names). Your Nighthawk router is providing DHCP service, via a single DHCP pool, for all devices.
Whilst your business devices are served presumably via WiFi from your Nighthawk Router, I surmise that you have a single “flat” logical network for everything - with no network or VLAN segmentation.
On the basis of experience with a similar network set-up, I suspect that the Nighthawk is periodically clearing its ARP table - and is effectively losing track of upstream client devices that connect via the AirPort Express. Upon expiry of the DHCP lease, DHCP traffic derived from the AirPort are being lost; loss of client device network connectivity will likely correspond with the DHCP lease time, as configured at the DHCP server (your Nighthawk).
Whilst you are unlikely to be able to control expiry of the ARP table maintained by the Nighthawk, you should be able to configure the DHCP lease time. I suggest that you significantly shorten the DHCP lease time. The aim here is to use DHCP as a “keep alive” for client devices tracked by the Router ARP table. Reducing the DHCP lease time should not cause material impact to network performance.
Your alternative work-around is to configure static IP addresses - removing reliance upon DHCP.
Returning to diagnostic exercises, a possible alternative with which to demonstrate normal operation of your Apple devices, is to simply allow your Apple devices to join your Nighthawk WiFi network.
Aha - and here lies your likely problem.
As a diagnostic exercise, remove the AirPort Express entirely from your set-up - and use your Nighthawk Router alone to provide WiFi networks.
Notwithstanding the diagnostic exercise that I recommend (consider that I am attempting to diagnose your issue remotely - and without benefit of a network analyser connected to your network), I suspect your issue is in part due to your Nighthawk and AirPort having a potential issue with DHCP and ARP.
How may IP Addresses are available to your DHCP Address Pool?
Thanks, but that’s not the issue. First off I have tried that, no change, second, my 3 MacbookPro computers and 5 iMacs and 2 Mac Pro computers, plus wireless printers etc, all work fine with no 169 issues, ONLY iOS devices are having this problem.
The Nighthawk is already providing a secure wireless for my business, which is totally separate otherwise. The Airport express networks are not secured. This is in a large house with no other houses nearby, so security is not an issue and I want visitors to be able to just log in, there is zero cell service, so everyone needs WiFi.
I could try doing that, but it is complicated, I also have 2 Netgear EX7300 wireless ex-panders, tied to the airport express wifi. Again, until recent IOS updates this all worked perfectly.
OK, THE Airport is in bridged mode, so it should just pass DCHP right along. I understand the longdistance diagnostics, and I will attempt to try it, I was just stating that to test this is a long and complex procedure, as I have to disable the airport express and reprogram 3 different wifi extenders that all were relying on the Airport express signal. then all my wifi devices need to be checked and connected to the new Wifi.
then after the test, which I will have to run for a few days in order to know that it is actually working correctly, then I would have to re-engage the Airport express and again reprogram the 3 extenders and reconnect all my wifi devices and wit a few days to see what happens. Meantime, currently, if I simply program my ios devices to manual i.p. addresses they work fine with the Airport express, extenders etc. So you can see why I am hesitant to do all this work, only to in fact discover it is an ios problem, and especially since, I found this discussion because others had the same issue.
Your understanding of my network is exactly correct. I will try the lease time change you have suggested and see what happens. I appreciate your thoroughness in following this.
I will check back in after I see what has happened. I still find it interesting that only iOS devices are affected, I have an Apple TV and 2 laptops signed into the WiFi via the extenders to the airport express and they seem to have no problems
…and your subnet mask?
255.255.255.0
ethernet connection
When it is all set to automatic, that is exactly when this problem erupts. If I set each device manually to 192.168.1.x and set dns manually to 192.168.1.1, then they stay put and work. If I set them to automatic, either they fail immediately or they first get a 192 address and them some hours later the stop working as they are now 169.xxx. Again only iOS devices, all are most current iOS versions. Including my watch most current update. This is extremely frustrating. My setup includes an Apple airport express which is creating the WiFi networks, but is not a router, it is in bridge mode coming off of my Netgear Nighthawk router.
This is happening on all my iOS devices, all the time
