Router suddenly has IP Conflicts due to failing DHCP reservation
Good morning,
this morning I got alerted by my NAS telling me about an IP conflict. Shortly after, I've noticed that the router gave the same IP to another device and all my DHCP reservations are gone. I then rebooted the router, without solving the problem. After that I tried to re-enter the DHCP entries which always got denied by " Diese IP-Adresse ist bereits für ein anderes Gerät reserviert. Bitte verwenden Sie eine andere." / "This IP address is already reserved for another device. Please use another one."
(the single entry disappears as son as another page is selected)
Then I installed a slightly older backup configuration without changing the issue as well. As a little quick and dirty workaround I've then changed the DHCP range to something different with a very short lease time, rebooted, to get rid of the IP conflict. After that changed the range and lease time back to before.
- How is it possible that the DHCP entries are not shown anymore, but still seem to exist but not working?
- What to do to get it relivable working again?
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Hello @Sten87
Thank you for reaching out to us and welcome to the TP-Link community.
How many Address Reservation rules have you created for the local devices? Do you also configure IP & MAC Binding for them? Be sure there is no conflict when configuring the two features.
Is the NAS connected to the AX73 directly via LAN? Are there any other extenders or switches in the network?
BTW, is the LAN IP of the AX73 192.168.69.1?
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Hi @Kevin_Z
to answer your questions shortly:
> How many Address Reservation rules have you created for the local devices?
As far as I remember there should be about 4 reservations, 2 Raspi's, the NAS and my HUE Bridge. Since their apps don't work correct and the NAS wants a fixed IP, I would expect them to see in the DHCP settings.
> Do you also configure IP & MAC Binding for them?
Not as I'm aware of, but I saw it enabled.
> Be sure there is no conflict when configuring the two features.
Apparently they where enabled both without my knowledge/remembering it.
> Is the NAS connected to the AX73 directly via LAN?
Almost, the NAS is on a simple TP-Link switch which then ends in the router.
> Are there any other extenders or switches in the network?
There's my VF Modem/Router before that but not connected to anything else nor DHCP server or something.
> BTW, is the LAN IP of the AX73 192.168.69.1?
Yes
As the chat support suggested resetting the router and start from factory default, I've been checking all the available settings to take notes and screenshots where possible for the new setup. There I've stumbled across the IP & MAX binding setting where a couple of entries were set, apparently. I couldn't explain why they have been set, as i don't remember it at all, but after they are deleted it's been possible to enable the DHCP reservation again. This raises a few questions in my opinion:
- How is it possible that the IP & MAC binding was on without me knowing? Im a regular user of the Tether app and didn't found these settings there?
- Why did the IP & MAC binding prevent me from setting up the apparently empty DHCP reservations without telling me properly?
- How can a configuration become so faulty that the already bound IP .100 gets assigned to another device month after its initial router setup, especially if it's bound to my NAS already?
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Thank you very much for getting back with the detailed info.
Just want to be sure again, are the NAS, Raspi, and Hue Bridge connected to the AX73 via a switch? What is the model of that switch?
Since the issue you are reporting is quite weird, I cannot answer why it happens but instead, I would escalate the case to the support engineers, they will investigate and analyze it further and provide a solution. Please kindly wait for the email contact from them.
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Hi @Kevin_Z,
Just want to be sure again, are the NAS, Raspi, and Hue Bridge connected to the AX73 via a switch? What is the model of that switch?
> The NAS is directly connected to the router, the rest is connected to the switch which is then connected to the AX73.
> The switch is an TL-SG108(UN) 8 Port Gigabit Desktop Switch v4
> Maybe I should mention that the NAS has static IP as the NAS and it's Services require a static one and the DHCP reservation can only be done within the set DHCP range
Since the issue you are reporting is quite weird, I cannot answer why it happens but instead, I would escalate the case to the support engineers, they will investigate and analyze it further and provide a solution. Please kindly wait for the email contact from them.
> The support chat I spoken to the same day also has a screenshot and my router configuration from that day. Which has this weired issue with the MAC Binding enabled and the DHCP reservation not working
Just to be clear, disabled the IP & MAC binding (which I'm at least not aware of enabling) and playing with the DHCP settings solved my IP conflict issue after all. The only thing what actually bothered me is the nonsense error message at the attempt of setting the DHCP reservation again + the MAC binding apparently not working and causing an IP conflict the day my backups are supposed to run.
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@Kevin_Z In the meantime, the chat support came back to me via mail with the recommendation to not use DHCP reservation and IP&MAC binding together. I've disabled IP&MAC binding in the web-frontend and a few days after I returned to the web-frontend, and it was enabled again. I start to believe that there's a bug somewhere, but it's hard to catch him
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Thank you very much for getting back with the detailed information once again. The issue you described is quite weird, generally, the Address Reservation won't change other settings like IP & MAC Binding. It's suggested to report and discuss the issue with our engineers via email, they will work actively to find it out and provide a solution.
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