Conflicting DHCP when Deco in AP mode ?
Today I ran into an issue which made me almost cringe.. as I hadn't expect this to happen, considering I've been working in the IT networking business for over 30 years..
I had recently purchased a Deco M5 mesh set with 3 nodes and setup as AP access points, because I alread have a decent router from my ISP (Zyxel EMG2926). This has been working fine for the last 6-8 weeks and nothing to complain about.
Last night, for some strange reason my router rebooted and I lost Internet connexion from everywhere, including my wired PC's which I use every day to work from home.. So getting back internet was critical to me and I tried the quick obvious options like rebooting the router and also reseting to factory the router, then reloading the configuration I had on backup.. To no avail, I wasn't able to get an functional internet, still the router diagnostic was able to ping any IP address outside my network.. Since I needed to work and support clients, I disconnected the Zyxel router and put back the Mercku M2 Hive base I had prior to the ISP router and after 5 minutes, was back into business.. (The Mercku is also a Mesh Wi-Fi system with 4 Bee nodes, albeit it wasn't working to my entire satisfaction, thus the purchase of the Deco M5).
Having spend the morning with work, I had hope the issue with the router might have been on the ISP side, so tried to set it back in action. Result was identical and nothing was really working.. Put the Mercku M2 back for the PM as I had a support call and did need internet ASAP.
At the end of the PM I got back to my router and it was so weird that I even tried to reset the Zyxel for the n-th time and start from scratch.. What puzzled me was that it was working if I forced my computer into fixed IP address, and even with DHCP Mac address reservation, the router wouldn't route my requests properly to the internet.. Looking at the IP addresses in the config made me think that router was totaly corrupt and crazy.. The router's IP is 192.168.127.1, but returns 192.168.127.102 as gateway and .254 for the DNS server, which is even crazier.. This is when I started to scan my network for rogue devices with my Android smartphone, but couldn't find anything suspicious. I've a lot of IoT devices and aside of the 3 Deco M5 AP's, there was nothing un-usual. However, the .102 IP address made me tick and look closer at the Mac Address, to finally discover that the main Deco M5 unit (the one connected by Cat5 cable to the switch) was the culprit.
For some obscure reasons my Zyxel router was thinking that the Deco M5 AP unit was the master DHCP on the network, despite TP-Link saying in their documentation that it is not the case when in AP mode.. As a proof, my Mercku M2 router had no issues at all with that and was perfectly handing over IP addresses to all devices..
Has anyone run into such a situation with another HW router ? getting conflicting DHCP server mode while the Deco M5 is in AP mode ?
I fixed my problem my disconnecting the Cat 5 cable temporarly from the switch, rebooted the Zyxel router and voilà.. after it was back as 'master' DHCP, I plugged the Deco M5 back and all was working as before.. But I'm really curious about that strange behavior.
Any comments are welcome on this.
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I don't know for the official releases, but for my X20 they provided a beta firmware which works. Smart DHCP stays disabled on my configuration.
So I am clearly afraid of updating the firmware l I don't do it as there are no new features anyway... so it's ok. But i agree that next time, not sure TP-Link will be chosen for mesh at home.
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@frederikk but 4 years in and it's still not consistently available in final-release firmware for all models that have this most ironically titled "Smart DHCP" feature.
In AP mode there should be no services offered. It's that simple. I have no idea how tp-link have managed to make this one simple requirement into such a farce.
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Still pretty irritated at the wast of time this has been...
Before I found this thread, I spent many hours being gobsmacked at the sudden appearance of unexplained (and wrong) DHCP router addresses killing intenet access for every DHCP device on my network.
It was really hard to locate the rogue DHCP server was but it eventually came down to the Decos. Turns out that that these devices, if they don't detect another DHCP server at startup, and even when set on AP mode, will automatically start up their own DHCP server!
So on Decos' "AP" mode is, um, is sorta' but not really AP mode.
This undocumented "Not really AP mode" is not 'smart,' it is ridiculous. In the (rest of the) universe of wireless devices, selecting AP mode means the DHCP. SERVER. IS. TURNED. OFF. This so-called 'Smart DHCP' would be funny, a joke, except as someone once said, 'everything's funny until its happening to you.'
Selecting AP mode is supposed to mean the DHCP. SERVER. IS. TURNED. OFF.
Turns out that that when using a C4000XG (Centurylink FiOS) as the upstream router, if the DEVOs (set up in "AP" mode) come on before the C4000XG's DHCP server is running, the Devos' unwelcome "Not really in AP mode" DHCP server kicks on. Next, the C4000XG comes up, detects the Deco's running DHCP service, & to prevent multiple (conflicting) DHCP servers on the same subnet, automatically shuts down its (correct) DHCP service... & BTW, I think that's smart. But now the Deco's "Smart DHCP" (giving out the WRONG router address) stays running.
And my network's stuck on Deco's bogus DHCP server and every DHCP device is spiked by an incorrect router address.
Comon' guys, let's fix it so that selecting AP mode on the Deco means its DHCP. SERVER. IS. TURNED. OFF.
Thanks for reading this, my "ventilation."
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Your challenge is that tp-link first got complaints about this in 2019. We're 4 years in and they STILL think this feature adds value. The ability to disable it is only on some devices and not necessarily available in final release firmware. That's the fruit of 4 years knowing this feature is killing people's networks.
Imagine if all you wanted was some dumb but RF-capable mesh APs to sit in an existing network, perhaps that network doesn't use DHCP and all devices are statically assigned. Well, tp-link thinks that's not your decision. They know best. Whether you like it, want it, or not, a DHCP server will be spun up regardless.
AP mode should NEVER have DHCP services running by design. If through user/owner choice you want some other DHCP service popping up that should always and only ever be an explicit choice when in AP mode. It should never have been a hidden, not really documented feature that surprised folks by breaking their networks.
Now all this has been said hundreds of times. The most astounding thing is that this "feature" is still present, still creating havoc and tp-link simply won't disable it by default in AP mode in ALL devices in final release firmware versions. Sell your kit and move on to something that's supported. Ironically the prosumer/business range of EAP devices from tp-link works superbly and I suspect an entirely different product team is responsible for that.
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Only "solution" I found was to buy a single M5 and put beta 1.6.1 on it https://community.tp-link.com/us/home/forum/topic/274630
Set it up as the master AP and disable "Smart" DHCP.
Not really a good solution and constrains better devices in the X range, but a workaround nonetheless. Not sure if M5 on 1.6.1 breaks other stuff.
Really shocking product design - no more TP Link kit in my future.
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I was one of the original users affected by this issue. I permanently by powering of my Decos, and removing them from my network. I had the M3 variety at that time and when they finally released a beta code, it was not for my M3. I still follow this thread to see if they ever announce they fixed it for real.
I will never buy or recommend another tp-link product over their way they handled this issue. I thought Netgear was bad for not providing a longer free support period on their products. So, choose. Buy something else. Avoid TP-Link. What good is support if they don't help anyway.
Good Day
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@phillip_mcmahon @atca @mccabet
There are plenty of models which have added the option to turn on/off smart DHCP under AP mode on the latest official firmware:
Deco Firmware Updates Adding Signal Selection and VPN for Multiple Models
Thank you very much.
best regards.
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And you're still blindly defending this position after 4 years.
People TODAY are still having their networks disrupted through a simple but dangerous design decision.
If you can state today that ALL models with the ability for "Smart DHCP" have it disabled by default and for ALL models this is available in final release firmware then tp-link is finally in a good place. After 4 years. But we know this isn't the case.
Why are tp-link so insistent on defending this feature when your paying users tell you what chaos it is causing on their networks????
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While I am also affected by this issue (and I cannot disable it on m4 V2), I doubt it will ever be disabled by default.
My understanding is that the deco series is by design meant for BFUs. As such, they lack many very basic settings, e.g., selection of WiFi channel. Most of BFUs probably do not use AP mode at all. And even if yes, TPlink might be worried of receiving support request for not being able to connect to the units because the external DHCP server failed.
Thus, I believe that the issue is actually elsewhere. It lies in the presentation of the Deco series by TP-Link, they should have mentioned explicitly not only what are they good for, but also what are their limitations due to the design (of course, they can link to their other products). But since this was not (and probably has not) been done, I feel that we are all trapped by this bad decision.
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