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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The biggest issue with turning on router mode and letting it do it's thing, is they crippled the M3 I have by only giving it a 100MBit ethernet connection.
If it had a Gb ethernet, then it's performance would be better and I would not have a problem with it.
Some may say the the Internet connections are not that fast, I have fiber and have 1Gb connection to the world. Why would I slow it down to 100Mb?
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@mccabet @DeGeekIT @PhilippeC @DomTheRag @J.Eng
Hello all, apologies for the super late reply.
As replied in this thread:
https://community.tp-link.com/en/home/forum/topic/160293?replyId=474556
We have noted this disable the smart DHCP feature on the Deco devices and we have already forwarded this feature request to the developer months ago, we hope our customers be more patient and keep an eye on the Deco app or the official website for the updates in the future.
You would think it would be simple and straight forward when adding the on/off switch but it's not. Disabling the DHCP server completely on the Deco device will lead to a risk that you lose the control of the Deco network when your front-end modem/router fails to do his work, you will need to reset the whole Deco system in order to make it work again.
Again, however, this has been added to the features requests.
Good day.
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@TP-Link_Deco
In a way the problem isn't the fact that, as an emergency measure, the decos hand out IP addresses when the upstream router loses internet connectivity. The core problem is that the Deco's don't force the clients to requests an ip address from the upstream router once it regains a connection.
I'm not sure, but I wonder whether this could be solved by the Deco's setting an extremely short lease times on the IP addresses, polling for an internet connection every few minutes, and immediately disactivating it's own DHCP server as soon as it discovers a viable internet connection.
My thought is that then all connected clients would be forced to request a new IP address from the upstream router very quickly once it had recovered.
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No, no and more no.
Bridge mode is meant to be passive. No one wants any service springing up, however sane the defaults might be.
tp-link could easily highlight the consequences of bridge mode, let the paying customer who is responsible for their own network accept this and then get out of the way. Every other device I've used in bridge mode operates like this, no idea why tp-link want this hybrid mess.
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I agree that when in bridge mode, your in bridge mode, no DHCP.
If I am also in bridge, I should be able to define my local address for the decos. That would let me access them when my DHCP serve goes down for some reason.
There is no way for a DHCP server to force a client to do anything. The client has to make a request, then the server replies with an offer. Short lease times is the only way to get an address after that happens. Problem is primarilly windows, it does not want to release an address if it had it. It always requests the last address it had in the discover.
If you think about it, since the Decos have a DHCP Client built in, they could do a DHCP request on the LAN to see if a DHCP server is on the network. That would give them all the network parameters, and primarily let them know there is another server present and not to enable its DHCP server.
May not be 100% fail proof, but better than what is available now.
I have no problem with a factory reset if I need to.
Until there is a fix, mine has been turned off. I may re-enable it someday for the grand kids on a guest network so it does not kill my primary network.
Now if they would only update the firmware for my TPLink AX-3000 Router to become part of the mesh, it has a GB connection.
Wishful thinking. Lets fix the current problem...
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I realize that by disabling DHCP Server there might be a situation where no device is handing out dynamic IP assignments then it might be possible for the Deco to be inaccessible.
Anyone who knows enough to set the Decos to AP mode (and turn off the DHCP Server) should also know how to assign Static IPs to his own subnet and access the Deco.
I mean, come on, isn't that how proper Access Points are supposed to work since the beginning of Wifi history? Isn't that how it's called in the Deco app? I'm pretty sure it's called ACCESS POINT MODE.
Rogue DHCP Server springing up to life (seemingly) randomly and then screwing off the whole network. That's a big headache to any network administrator.
Give us an option to completely toggle off the DHCP Server in the Decos.
Just put a warning there to scare off the ones who don't really understand about dynamic IPs and DHCPs.
I'm sure there's plenty of workarounds you can do.
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Same issue here.
TP-Link MUST solve this.
I got multiple LAN losts before finding this thread and aknowledging that it was not a faulty configuration on my side which was responsible of all the mess.
We need answers.
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+1 on the disable option
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