Tipo874 wrote

I have installed Deco M5 sets both at home and in the cabin. I run them in AP-mode and at home I have a Solaris server providing DHCP service, and in the cabin it is my LEDE based router doing the same.

I have noticed what appears to be a bug where the Deco master appears to switch to router mode after a power outage and starts handing out non-working IP addresses to clients if it doesn't find a DHCP server during boot. To get things working again I need to pull the power from the Deco master and reboot the router or solaris server so that the DHCP services are available before powering up the Deco master again.

Is this a known issue?

I have encountered exactly this problem too now in a similar setup at home, so yes I would say that this is a know issue, however after reporting this issue to TP-Link Support via e-mail the reply was not encouraging. Their support staff clearly lack the skills to recognize this this is a firmware bug an instead suggested that I should change the IP address of my Asus router from 192.162.1.1 and set it to a other subnet such as 10.10.10.x which the very suggestion pissed me off as such a poor reply that I more or less demanded that they send this up the chain and get the issue replicated in a lab by their developers and that the fix the problem in the firmware as this is obviously a firmware bug.

Here is a copy of my initial report to to TP-Link Support via e-mail

Deco M5 AP mode messes up DHCP on Decos after a power outage

I have installed a set of three Deco M5 at home. I run them in AP-mode and at home as I have an Asus router providing DHCP service. I have noticed what appears to be a bug where the Deco master appears to switch to router mode after a power outage and starts handing out non-working IP addresses to clients if it doesn't find a DHCP server during boot. Rebooting all the Decos did not help, and neither did powering them all off and powering them back on one by one after rebooting the Asus router.

To get things working again I needed to switch the master Deco to router mode and then back again to Access Point mode. After this I however get problems with the non-master Decos which just keeps rebooting again, again and again. Is these known issues? I read in your forum that at least one other person with the same setup have stumbled on the same issue after a power outage.

Only one Deco (the master Deco) is connected to my router. The other two Decos are wireless on twi other floors in my house where I have no ethernet wires at all. I have even tried to remove and reset both non-master Decos and I still have problems now.

Link to a thread in uour own forum where a other person with same issue => http://forum.tp-link.com/showthread.php?104512-AP-mode-messes-up-DHCP-after-power-outage

I cannot imagine that this problem would be hard to replicate by Deco developers in a lab by just setting up a similar AP-mode installation with only the master Deco connected via ethernet wire to an third-party router, just simulate a power outage and make sure that the Decos are fully booted before you power-on the router. I do not think that a picture is needed since my installation is such a simple setup.

FYI; I am an IT-technician myself for over 15 years (senior system engineer for Windows and Linux servers specializing in virtualization. So I am fairly technical and have no problems following technical jargon.

Regards / Andreas

Hi,

If you manually restart the modem and Deco, will the issue happen as well?

No hell from TP-Link support. They replied that since their engineers had tried this setup before initial release of the product they will now not even give it an honest try to replicate it today. Very unprofessional answer. Useless support. This is clearly a problem even if it can not be replicated everytime. A good developer should be able to solve this in code without replicating just by making sure that DHCP and gateway services never ever start when in AP mode.

flying snow wrote

If you manually restart the modem and Deco, will the issue happen as well?

First of all, this problem does not happen on every cold boot, only sometimes. However in theory you should not see this issue if you manually restart/start your router first and make sure that its DHCP is fully started before you restart/start the master DecoAs it is now I would personally not recommend buying a Deco until TP-Link to run in AP-mode until they fix this problem in firmware, which might be never as their support for this has been useless to date. You can also see that this problem have been posted in thier own official forum for over a month now and a TP-Link representive have not even replied yet. In fact, with this level of support my recommendation would be to never by a TP-Link if you want post-sale support.

No help at all from TP-Link support. They replied that since their engineers had tried this setup before initial release of the product they will now not even give it an honest try to replicate it today. Very unprofessional answer. Useless support. This is clearly a problem even if it can not be replicated everytime. A good developer should be able to solve this in code without replicating just by making sure that DHCP and gateway services never ever start when in AP mode.

flying snow wrote

If you manually restart the modem and Deco, will the issue happen as well?

First of all, this problem does not happen in every cold boot, but only sometimes. However in theory you should not see this issue if you manually restart/start your router first and make sure that its DHCP is fully started before you restart/start the master DecoAs it is now I would personally not recommend buying a Deco until TP-Link to run in AP-mode until they fix this problem in firmware, which might be never as their support for this has been useless to date. You can also see that this problem have been posted in thier own official forum for over a month now and a TP-Link representive have not even replied yet. In fact, with this level of support my recommendation would be to never by a TP-Link if you want post-sale support.

As this problem persists I have been diagnosing the issue and been in contact with tp-link support, who has been helpful.

 

It turns out that the Deco starts offering dhcp when it notices that the main dhcp server goes away. My router runs OpenWrt/LEDE and the dhcp server (dnsmasq) issues a couple of DHCP Dicsovery queries to make sure that there are no other dhcp servers on the net, and when it receives a response from the Deco, it gives up.

 

Up until now I have worked around the issue by logging into the switch and disabled the ports to the Decos and then I've restarted the dhcp server on the router, and once it is properly up and running I could enable the ports again, and it work work fine until a power outage or a router reboot.

 

Today I found a "force" option to the dhcp server, which disables the startup tests so that it will start despite having the Deco also acting as a dhcp server. The deco will disable the dhcp services once it sees that the routers dhcp server is up and running. I have only tested it once, but it worked fine the, so I think this will be a workaround for now.

 

So for those who are running OpenWrt based routers and Decos in AP mode, who are having issues with dhcp after a power outage, add an "option force 1" for the lan setting in /etc/config/dhcp on the router.

 

I still think it is a mistake to have the Deco start offering dhcp in AP mode.

THANK YOU for this tip to force dnsmasq to continue serving DHCP. Until TP-Link gets around to implementing an option to disable DHCP entirely in AP mode, this is a lifesaver.