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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Hi, thank you very much for getting back to us.
After checking your first post, I did not see your model number yet.
Could you please send me a private message about your TP-Link email ID and MAC address of your main Deco?
May I know the model number of your main router as well?
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Over 2.5 years since this problem was first reported and you're still wasting people's time by asking them to supply information related to the mess "smart DHCP" is causing, and STILL promising a fix at some point.
It's super clear, when in AP mode your devices are 100% transparent on the network. Not a single should ever pop up and do its thing. That is what AP mode and it's what people want and expect. Trying to working out what triggered smart DHCP and tuning your algo to avoid this is MISSING THE POINT. It should not be there in the first place.
Why is it taking so long to provide a toggle option to fully disable all features in AP mode? Better yet, AP mode should be set like that by default, we should have to toggle features ON in AP mode.
You've totally ruined an otherwise decent piece of hardware with the M9. Notice that none of your competitors offer such silliness when their products are in AP mode.
Talk with your colleagues in charge of the EAP range of access points. There's no such silliness happening there either.
When are you releasing a fix for this horrific design decision?
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I had the same issue and my local IP range got totally different... some devices in 192.168.50.X IP range and some others in 192.158.8.X... the hole LAN network should work only in router's IP range not a total diff one that came up out of nowhere.. OH, YES from somewhere: your "smart" Deco built-in DHCP server
fix it
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Hi, you could try to install the beta firmware here and it has added the DHCP on/off switch under access point mode.
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@Jay_Jay
Hi, I got this message from TP-Link with link to beta firmware:
TP-Link: Hi, thank you for your attention. I happen to have a beta firmware which added DHCP on/off switch under access point: https://static.tp-link.com/upload/beta/2021/202109/20210928/M4_V2_1.4.3_disable_DHCP_in_AP_mode.zip But please do not update to the firmware 1.5.x later, since 1.5.x does not add this feature yet and it could not be downgraded back to 1.4.3.
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Hi, I see that you also have Deco M5 which Is on firmware 1.6.0.
So when Deco M5 is working as the main Deco under access point mode, there is no need to install any beta on M4.
You could turn off the smart DHCP switch on M5, then M4 will sync with the same configuration.
Thank you.
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