@pdfowler 

This also occurs in the M9.  When rebooting the main router (not deco) with the DHCP server (which is sensitive to other DHCP servers on the network), or even sometimes just restarting the DHCP server on the router, the M9 will decide to become the DHCP server.

The main router (again, not deco) is smart enough to know there shouldn't be 2 on the network and refuses to start, which as the users above noted collapses the network.

We have 130+ devices on the network.  When using the M9 in access point I NEVER want it to enable a DHCP server.

How can I keep it from doing that?

I'd assign the main deco a static address if that were an option, but there is no control over it from the AP...only whether it is in AP mode or not...and when in AP mode, it would NEVER be the case that it should act as the DHCP server.

@Blueman2 they are not stupids, they got their money. 

@Sol I don't have my deco's anymore, but... is it possible to reduce at one the range of the IP's pool? i.e.: use the same begin and end address for the DHCP address range. It doesn't solve your problem, but at least would minimize the consequences.

My advice: sell the Decos, I have nothing against TP-Link, but the Deco's architects did the specs a Dec.26th after drinking too much.

I replaced them by access points from Omada series from...TP-Link, they work fine for me.

Actually, they work so good that I don't remember them.

I have had so many issues with this stupid "smart" DHCP.  If I put it in AP mode, at no point ever should it enable its own DHCP server.  This has to be one of the dumbest configurations I've seen in a network device.

Add an option to permanently disable the DHCP server.  I'll be looking for a deal on a different system in the mean-time.

I noticed a sale going on for the new TP-Link x20 AP devices.  I was about to pull the trigger, then remembered the DHCP server issue with my M5's.  Never again will I buy TP-Link.  I just have to keep reminding myself of that!  ;)

@scassar @Kevin_Z 

After taking my router offline briefly to move it and having the Deco x60 "take over" my network, and losing several hours of sleep trying to figure out WTF happened, allow me to join the chorus of those requesting that it at least should be possible to disable this behavior.

I can appreciate that it is difficult to simultaneously target both the "nontechnical user" scenario and the knowledgable power-user segments at the same time, and that automation that the first group finds helpful the second may find very problematic. I think in this case though, the number of nontechnical users that will use AP mode is probably small, *and* this behavior is likely to be problematic for *both groups*. Handing out IP addresses in a non-routable range makes for very strange behavior. If primary DHCP is down on a network, its owner will probably already be aware of and trying to fix it, because all sorts of other stuff (e.g., wired stuff) will be borked. The Deco's behavior was written with good intentions but with tunnel vision as it will make solving the actual problem just that much harder.

I thought I'd share what I've done to hopefully mitigate this behavior until TP-Link has a fix. In my router I have opened up my netmask (to 255.255.248.0) to allow 8 class-C ranges starting at 192.168.8.0 to be routable to the internet. My router's DHCP server is set up to assign dynamic addresses under 192.168.8.* only. I've also set up IP reservations for my 3 Deco units under a different, but still routable, range, 192.168.9.1, .2, and .3. For further insurance, with the main Deco in router mode I manually changed its IP to 192.168.9.1 (then switched it back to AP mode). My hope here is that in the event the Deco loses its mind and brings up its DHCP server, it will at least do so within 192.168.9.* - a range that is routable to the internet *and* doesn't conflict with my own network's dynamic DHCP range.

I am hoping this will prevent the Deco from handing out IPs in its 192.168.68.* default range which totally borked my network as those are all non-routable IPs.

But please, TP-Link, fix this. Good experiences with your previous products led me to buy the Deco, and I am very happy with its WiFi performance, but this "feature" is really ill-conceived.

@Kevin_Z 

Please make a switch to turn off this 'normal behavior'. Perhaps it works well for >50% of  your customer base, but it gives huge problems to anyone with multiple devices (both wired and wireless) in a home network. About: 'the DHCP server on Deco will be disabled automatically again...' - pretty sure this feature doesn't work or I wouldn't have just spent another hour fixing this problem.

At least I'm glad I found this thread. I now know I have to switch off the main deco before I reset the router.

I do agree that AP should not behave as DHCP server in any scenario. If true DHCP server is down, it means in most cases user ISP gateway is down, too. It is a bigger problem for home user than smartphone or other device unable to acquire IP address.

Yet, I can't figure how people manage to trigger "smart" DHCP in their environment so easily. I run my Deco mesh for over a month already, in AP mode only, restarted my ISP gateway few times to correct its issues - haven't triggered wrong IP address allocation.

Perhaps, it is because my ISP gateway has "DHCP Lease" set to very long period, which makes very unlikely for device to request IP address at exact moment when ISP gateway is down. I can also set "DCHP Lease" to "Forever" but I am reluctant to - might try it if I get into same issues described on that thread.