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DHCP IP Address Conflicts on Reboot

CoffeeAndTech

2 weeks ago - last edited a week ago

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DHCP IP Address Conflicts on Reboot

2 weeks ago - last edited a week ago

Tags: #VLAN & Multi-Networks #WAN Setup #DHCP Service

Model: ER7206 (TL-ER7206)

Hardware Version: V2

Firmware Version: 2.1.3 Build 20241030 Rel.55760

I recently upgraded from an ER605 v2 to ER7206 v 2.26. I removed the ER605 and adopted the ER7206. Router is setup with a 192.168.1.1/24 (default) and 192.168.2.1/24 (IoT network) interfaces. DHCP assignments are 192.168.1.100 - 192.168.1.254 and 192.168.2.100 - 192.168.2.254, respectively.

On reboot, I am getting about 10 - 15 IP address conflicts: An IP conflict detected. Warning. Router client[MAC Address] client[Mac Address] used conflicted ip: 192.168.1.102.

I don't have a second DHCP server on my network. I wasn't getting these errors on the ER605.

Any ideas what's going on? Is it possible I didn't do the migration correctly? I know I had a few areas in my initial migration where the WAN port was defaulting to the SFP/WAN1 when my WAN port was actually WAN2. I updated the config and things seemed to work fine. Outside of that, the migration appeared to go smoothly without error.

Any help would be very apprecated!

16 Reply

CoffeeAndTech

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a week ago - last edited a week ago

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Re:DHCP IP Address Conflicts on Reboot

a week ago - last edited a week ago

@CoffeeAndTech

#14

Clive_A

a week ago

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Re:DHCP IP Address Conflicts on Reboot

a week ago

Hi @CoffeeAndTech

Thanks for posting in our business forum.

CoffeeAndTech wrote

@Clive_A

These warnings are coming wireless devices. Here are two examples:

1) Conflict between a Macbook Air (connected to EAP_1) and an iPad (connected to EAP_2)

2) Conflict between an iPhone (connected to EAP_3) and an unknown MAC ID (suspect an iPhone) (connected to EAP_2).

What is interesting is that they are on different TP-Link EAPs (EAP650s).

I tried setting my lease to 2 hours and then also to 7 days. Either option didn't seem to make an impact on the problem.

That does not make too much difference to me. These pictures are generic config. I don't find anything wrong with them.

I want to know if you simplify your network, will this error disappear? Remove other devices and keep the AP and the router, and monitor if this persists.

A diagram of your network is required.

A screenshot of your DHCP reservation page.

Does it only happen to certain devices? Or everything is randomly getting the same IP?

What's the network config like on affected devices? I want to learn about it.

Best Regards! If you are new to the forum, please read: Howto - A Guide to Use Forum Effectively. Read Before You Post. Look for a model? Search your model NOW Official and Beta firmware. NEW features! Subscribe for the latest update! ☛Download Beta Here☚ ☛ ★ Configuration Guide ★ ☚ ☛ ★ Knowledge Base ★ ☚ ☛ ★ Troubleshooting ★ ☚ ● Be kind and nice. ● Stay on the topic. ● Post details. ● Search first. ● Please don't take it for granted. ● No email confidentiality should be violated. ● S/N, MAC, and your true public IP should be mosaiced.

#15

CoffeeAndTech

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a week ago - last edited Saturday

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Re:DHCP IP Address Conflicts on Reboot-Solution

a week ago - last edited Saturday

@Clive_A

After a lot of research, I determined this was a result of a few smart TVs that were holding on to their IP leases and not requesting a new IP from the server even after their lease was up. No problem with the router or setup. I forced an IP renewal on these TVs and it solved the problem. Thank you for all your help!

Recommended Solution

#16

ginoue

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Saturday

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Re:DHCP IP Address Conflicts on Reboot , and DHCP Reservations not assigned.

Saturday

@CoffeeAndTech
I got these errors after the latest firmware upgrade, and boot.

tp-link oc200 as controller and er7206 v2 gateway
dhcp reservations not working anymore.

OC200 firmware v5.15.8.12

ER7206 v2.0
Firmware 2.1.3 20241030 release 55760
-
Going mad I did a total reset and started all over.
Setting up the gateway :
ER7206 v2.0
and setup DHCP and reservations..

it all works.

Setup the OC200 and adopted equipment / wifi ap...
Still ok.
Adopted the ER7206 v2.0 into OC200
Now trouble begins after reboot ... and still if rebooting all other devices IOT etc.
All IP reservations are ignored and some assigned to multiple devices.
= = =
This configuration and same equipment workd until september 2024, then new firmware was installed - and after that IP conflicts could occure if some equipment were booted ... seems like the DHCP lease and dhcp assignment does no longer work on ip reservations.

This was also a bug back in 2.x.x firmware of ER7206.
Before using OC200 with another gw as dhcp this was NEVER a issue., so it must be a bug comming back into the ER7206 Gateway.

#17

CoffeeAndTech

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Saturday

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Re:DHCP IP Address Conflicts on Reboot , and DHCP Reservations not assigned.

Saturday

@ginoue Since I didn't notice any clients having connection issues, I suspect this was a change to logging in the OC200. I don't think it's an issue.

#18

CoffeeAndTech

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Saturday

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Re:DHCP IP Address Conflicts on Reboot , and DHCP Reservations not assigned.

Saturday

And I should add that I *did* have some clients on my network who weren't releasing their IPs even when I set a static IP and rebooted them. These were mainly smart TVs.

#19

DHCP IP Address Conflicts on Reboot

DHCP IP Address Conflicts on Reboot

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