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 think that's trying too hard to explain their design choice.
If their target market won't choose AP mode then it makes even less sense that those folks who explicitly chose AP mode are silently surprised when a DHCP server pops up which is GUARANTEED to screw up their network and generate support calls.
In the last 4 years, no one has provided a valid example of why this feature does anything of use in a network with AP-configured wireless.
Show me another basic consumer-focused wireless product that when in AP mode fires up a DHCP server. tp-link know it's stupid to do this, as it's not replicated in their EAP range where AP mode is as dumb as it should be.
vmonkey wrote
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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Just found this forum and it seems to explain a lot of the conflicting IP address problems I seem to be having with my newly installed S7 AC1900.
I recently upgraded to Vodafone Hi-Speed fiber and of course, received a new Vodafone router which I set up as the primary DHCP server for my network together with a fixed IP pool. At first, things went fine but then I decided to upgrade my old S4 Wi-Fi network which was limited to 100 Mbits and purchased the S7 AC1900 set which were set up as access points.
It did not take long for everything to start falling apart, especially my embedded IOT devices many of which had fixed IP addresses from the reserved pool. I have spent a week desperately trying to figure out why my reserved pool (as defined in my router's DHCP section) was getting corrupted and kept giving IP conflict messages.
Finally, in desperation, I switched off the S7 AC1900 as it was as far as I could see the only thing I had changed. Immediately the problem disappeared so I assumed the S7 had been giving out IP addresses despite being set as an Access point.
Although I have not seen the S7 AC1900 specifically mentioned in the forum I assume it has the same (stupid) smart DHCP system. Can anyone confirm this and is there a firmware update that fixes it?
If not, it is going back to Amazon as it is useless to me.
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This is also a problem—no formal mention of this dumb feature in the primary product documentation.
Save yourself time and energy, return it to Amazon and go with something else.
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I also have this problem, it is so annoying and I am not able to use the Deco M4. Every day or so the M4 DHCP server starts up and allocates the incorrect IP addresses.
For me all was ok until I foolishly upgraded.
I have had them too long for a refund. I will have to spend more money on a better product, it will not be TP link that is for sure.
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I also just got stuck in this stupid DHCP problem at work, luckily in the system of 8 DECO E4 I got a few DECO E4 V4 that just updated the Smart DHCP button, and everything was resolved.
I’m lucky I don’t have to endure this for years like you guys.
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I just stumbled across this Smart DHCP undocumented feature a few days ago. The documents clearly state that several features - including the DHCP server - are disabled for AP mode in my M4 V2, so whose bright idea was it to add another hidden DHCP server that was fairly obviously going to lead to network instability? I've wasted a couple of days on this problem and still not managed to recover the situation completely. Will definitely be looking to replace these units.
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IanMK wrote
I just stumbled across this Smart DHCP undocumented feature a few days ago. The documents clearly state that several features - including the DHCP server - are disabled for AP mode in my M4 V2, so whose bright idea was it to add another hidden DHCP server that was fairly obviously going to lead to network instability? I've wasted a couple of days on this problem and still not managed to recover the situation completely. Will definitely be looking to replace these units.
You should be able to turn off DHCP server running in AP mode after installing firmware from that link: Deco M4/S4_V2 Support Connection Preference
You may only need to install that firmware on Main Deco.
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Thank you. I'll try this when I get a moment. This fix needs to be published in a formal release as soon as possible.
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I also have this problem, it is so annoying, everything was working before I upgraded the firmware and it messed up my network. My router reboot frequently because of it, if I disconnect them, no more problem. I have had them too long for a refund and would not have chosen TP Link if i knew it would cause such issues. Please fix it !
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