@Scuba_Diver 

Hi, I'm a user from the UK.
 

I've checked my Deco M5 system, and all units are currently running on firmware version 1.9.0 (build 20250722 Rel. 56822). I'm not sure how my system was updated to this version, but it appears to have jumped from the 1.8.5 build.
 

I tested the guest Wi-Fi late last night and can confirm that the issue persists. The main and IoT networks are working fine, but devices connected to the guest Wi-Fi have no internet access.
 

Regarding the beta firmware, I don't intend to install it on my system. As a consumer, I believe this level of beta testing should be handled internally by TP-Link, not passed on to customers. This situation further highlights a significant lack of quality control in your firmware release process.
 

While I am glad to see that this issue is being addressed, it's clear that this problem should not have made it to a public release in the first place.
 

  @David-TP 

Any reason why the beta firmware is not incorporated into the 1.9.0 firmware? 

Is there a 1.9.0 beta firmware that incorporates the guest network fix? 

Do you know if the 1.9.0 firmware has a dhcp fix? 

Thanks! 

@Scuba_Diver 

@David-TP 

I had the same issue with the guest network and do also have the same firmware as you (1.9.0)

@Slacker878 

No, the 1.9.0 still has the guest network DHCP issue

Quick workaround for the guests network not getting an IP: Disconnect the cable between your main deco and your ISP modem for a few seconds. All will work as normal after you connect the cable again. (until the deco is rebooted. In that case, you need to do the quick fix again. )

b.t.w. The issue only occurs when the decos are connected to eachother with a cable.

Regarding 1.9.0:

The 1.9.0 firmware was available to me 3 weeks ago and I installed it on 3 of my decos (M5) After a few days, I required my spare 4th Deco M5 and connected that one too. It detected an available upgrade and it got installed. But that was the 1.8.5 1.9.0 was not available anymore.

At that point I noticed the guest network issue and thought it was caused by the inconsistent firmware versions. but, as we know now, it wasn't.

The DECO app showed all systems had 1.9.0 --> when using the option "upgrade Deco" However... when checking the individual Decos, 3 showed 1.9.0 and one 1.8.5

I checked again today all the individual ones, and now all show 1.9.0 --> so in the last two weeks, my 4th deco got auto-upgraded too to 1.9.0

Hope this helps and yes: TP-Link, please fix this asap and deploy the new firmware

Greetings from the Netherlands,

Martin

  @Martin_NL After resolving the problem witb beta firmware that TP-Link support sent me, the system recently did an automatic "update" to the previous faulty version on all Decos, which knocked out the guest Network DHCP again (same problem with BootP port blocked). 

To make matters worse, it won't allow me to install the beta firmware now, so I am stuck without a guest LAN. 

I reported the problem to TP-Link support yesterday, and am awaiting a reply. 

  @eppy 

you can try disconnecting the cable between your main deco and your ISP modem for a few seconds. This solved the DHCP guest network issue for me and others. 
Do make sure you have the reboot schedule on your decos disabled or it will fail again after the reboot of the decos. 

I've been dealing with the same issue on my home network for a couple of years now. I was never able to pinpoint what ultimately caused or resolved it, but today, after trying the workaround suggested in this thread, I confirmed that simply unplugging and reinserting the WAN Ethernet cable on the main Deco temporarily fixes the problem.

What really concerns me is:

a) this issue has been recurring for years without a proper fix
b) it suggests a lack of quality control on TP-Link’s side
c) instead of addressing these core reliability problems, the focus seems to be on “premium” subscription features and third-party integrations (e.g., sending client MAC addresses back for identification)

With that in mind, how are we supposed to trust the platform long-term?