@GPGeek  same issues here with M5 deco's!

After turning on to AP mode the master deco gives dhcp addresses on the cabled and wireless network. IP lease with the gateway- and dns address of this master deco to the clients.

Rebooting is also not helping this out.

I have to turn back in Router mode otherwise my clients want get internet access because the Master Deco is not the gateway in my setup.

FIX this please it takes too long to solve this issue.

Thought it was worth adding to this thread that I've had this issue a couple of times now on my Deco S4 in AP mode. (hence I've been looking for information on this forum)

In my case the S4 spontaneously started handing out DHCP leases (which were wrong of course, because it cannot be configured in AP mode) and broke every DHCP client in my network. I'm 99% sure that there were no issues with my actual DHCP server (a Ubiquity edgerouter) at that time.

There are a number of threads on the forum about this and i'm shocked that anyone in TPlink though this was a good idea, let alone attempt to justify it. For the avoidance of any doubt rogue DHCP services break networks and the Deco units would be thrown off of any corporate network for that alone.

Is there any update on this fault and it's solution?

@arfur 

Of course there isn't an update. They honestly don't care about this at all.

Ditch the product and ditch the vendor.

@TP-Link_Deco 

Dear TP-Link team,

as I am suffering from exactly the same problem (rogue DHCP issues with multiple wired Deco units and Zyxel modem), I would like to suggest another idea that may be easier to implement on your side.

First of all, it seems the DHCP issue is triggered by particular Zyxel modems / firmware versions. In my case, while using my old ZTE modem, there were no issues whatsoever (confirmed by other contributors as well). My current Zyxel modem is VMG8825-T50, firmware version  V5.50(ABOM.4)b4_D0. The issue occurs only when the slave Deco is wired to Zyxel modem (Ethernet backhaul). In case of WiFi backhaul of the slave Deco, there is no issue whatsoever.

Obviously, Zyxel modem VMG8825-T50 exhibits some networking pattern (legitimate or not) that triggers the undesired DHCP action on Deco side. As a potential remedy, you can investigate the networking pattern of Zyxel and try to mitigate that on Deco side (i.e. make Deco less sensitive to Zyxel's networking pattern). Using this approach, you can resolve the issue while keeping your intelligent DHCP feature intact.

I hope that helps.

Best regards,

Igor

@IgorN77 

They won't do a thing. Plus this isn't limited to Zyxel modems. It happens to lots of people with different hardware.

The whole design is crap. I repeat, they won't do a thing, you're stuck with this junk.

Well, the whole discussion seems to be centered on disabling the DHCP server feature in AP mode, whereas an alternative solution (making the design less sensitive to external (modem-induced) network blips) was not considered at all, so I decided to bring it forward. Whether TP-Link is going to address the issue in one or another way, is a separate question.

@IgorN77 

The thread is 2 years old.

Making it less sensitive won't change the fact it's a fundamentally flawed design to throw up a DHCP server on a network and dish out IPs in range that 1) the user has no control over 2) IPs from a different broadcast domain.

It will do nothing but break your network.

@phillip_mcmahon 

I don't disagree, but I've recently realised that the IP range that the Decos fall back to is NOT totally out of your control. They seem to fall back on whatever range you used in the Decos the last time they were in Router mode. 

I'm currently experimenting with using the same IP range on my Decos as I use on my ISP router, reserving the same IP addresses for the same "difficult" devices on both the Decos and ISP router, before finally switching the Decos back to AP mode.

It seems to me that under the circumstances where the ISP router goes offline, the Deco's will then just provide the same address details to every device, and in theory that should work around the problem.

@IgorN77 @TP-Link_Deco

Please comment.

I bought tplink deco E4 and i searched on forum and I knew about issue " Smart DHCP". It is a big issue. I use DHCP on Windows server and relay to it from router. When reboot or can not connect to router, Deco E4 will automatically provide DHCP to user. But as Kevin say when main DHCP server came back, it will stop DHCP from Deco E4 but I did not see about this. User still get IP from Deco . I don't know any solution to fix it. It still cause a serious issue in my company to challenge me to fix it. Please for me solution to fix it soon. Thanks

Note: I use AP mode of Deco E4. And 80.148 la IP of AP Deco.