TP Link XE75 Access Point refuses to use DHCP server, stuck on 192.168.68.1

TP Link XE75 Access Point refuses to use DHCP server, stuck on 192.168.68.1

TP Link XE75 Access Point refuses to use DHCP server, stuck on 192.168.68.1
TP Link XE75 Access Point refuses to use DHCP server, stuck on 192.168.68.1
2024-10-11 05:20:50 - last edited 2024-10-11 19:49:03
Model: Deco XE75  
Hardware Version: V1
Firmware Version: 1.4.1 Build 20240722 Rel. 60491

I am currently losing my mind trying to get my network back up and running. I have 4 XE75 deco units with one unit dedicated to an isolated IoT network and the other 3 creating a mesh network for my home wifi. All of the Deco units are in AP mode and I use them with a separate router. The DHCP on the router is fully functional and my router is set up with a gateway/mask of 192.168.10.1/24

I've been having issues with my wifi 6 connections dropping, lan connections not working off the unit, etc, so I went to reset one of the units, but the satelite unit would not reconnect to the main deco. I then tried to plug it into the main deco directly to reconnect them and this somehow corrupted the main deco and rendered my entire network unusable (all devices showing red lights). I then decided to reset the main deco and recreate my home network from scratch. I was able to do this, but when I flipped the device into access point mode, the light went red and I was no longer able to connect to it via the app. I proceeded to do this a dozen more times over the course of the day and found that the issue was that the deco has an ip of 192.168.68.1 and for whatever reason is refusing to actually reach out to my dhcp server to get a new one. I've tried rotating all 3 of the deco units as the main deco and all of them exibited the same behavior.

It appears that flipping the deco to Access Point mode doesnt change the IP of the deco and smart dhcp constantly runs until i turn it off, at which point I lose access to it in the app unless i manually set my gateway and ip to the 192.168.68.1/22 subnet. That said, I am able to access the internet through the deco, so passing through it and getting an IP address from my dhcp server is working for every device except the deco.

I've checked the logs on both the deco and my dhcp server and I see zero requests coming to my router from the deco, and I can see the logs on the deco that udhcpc logs "Sending discover..." followed by tons of daemon errors, and then another "Sending discover..." until smartip reports "[lan] udhcpc detects fail". Then the 192.168.68.1 ip gets set. Again, every device that connects to the deco can get to the dhcp server, but not the deco itself, which means there is zero possibility that the deco is not capable of seeing the router. In addition, the IoT deco device, which is running on an older 1.2.9 Build 20240724 Rel. 39578 firmware, is the only deco without any issue at the moment. It is the only one that is not on the latest firmware.

I'm pretty frustrated at this point, I don't think there's anything I'm missing and the fact that all of the decos are displaying the issue after factory reseting them makes me believe this is a firmware issue, but if theres any official recommendations or help that could be offered before I start considering RMA or replacing my network backbone I would much prefer that option.

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Re:TP Link XE75 Access Point refuses to use DHCP server, stuck on 192.168.68.1-Solution
2024-10-11 19:48:14 - last edited 2024-10-11 19:49:03

I was able to figure out that the deco recently began prioritizing itself as a dhcp server regardless of whether there are other dhcp servers it can reach AND regardless of whether smart dhcp was even on. I initially kept smart dhcp on thinking it would be a nice fallback if my router went down, but since it never found my router it would just hijack all of the assignment responsibility. However, if I turned smart dhcp off, every device would find my router, but the deco would still just find itself. I put it behind a network switch and blocked its ability to respond to its own dhcp discover packets and this immediately caused the deco to grab an ip address from my router.

Anyway, thanks to all the tplink support staff that responded in this thread, without your help my internet would have been out for days while I was fighting my deco's black box rogue dhcp server even after turning it off. I'll be sure to recommend this device to anyone that has a network stack capable of fixing its abysmal shortcomings.

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Re:TP Link XE75 Access Point refuses to use DHCP server, stuck on 192.168.68.1-Solution
2024-10-11 19:48:14 - last edited 2024-10-11 19:49:03

I was able to figure out that the deco recently began prioritizing itself as a dhcp server regardless of whether there are other dhcp servers it can reach AND regardless of whether smart dhcp was even on. I initially kept smart dhcp on thinking it would be a nice fallback if my router went down, but since it never found my router it would just hijack all of the assignment responsibility. However, if I turned smart dhcp off, every device would find my router, but the deco would still just find itself. I put it behind a network switch and blocked its ability to respond to its own dhcp discover packets and this immediately caused the deco to grab an ip address from my router.

Anyway, thanks to all the tplink support staff that responded in this thread, without your help my internet would have been out for days while I was fighting my deco's black box rogue dhcp server even after turning it off. I'll be sure to recommend this device to anyone that has a network stack capable of fixing its abysmal shortcomings.

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