IoT network isolation on Deco X55 -- not possible
Almost three years ago, I bought a Deco X55 mesh system, and I was excited when I learned that it offered a separate IoT network. I was then very disappointed to learn that there was no way to isolate my IoT devices from my main network, which is a real security problem, since I have over 100 IoT devices in my home from many different vendors. I understand that there are some benefits to the features included in their Deco IoT network, but I (and many others) really need an isolated network for security reasons. I posted about this problem back then, but that thread has since been closed. Several other users added in that thread that they wanted IoT isolation as well, and the TP-Link folks said they would put it on their list of possible future features. Clearly this isn't hard, as they already do isolation on the Deco X55 Guest Network. However, nothing has happened on this front. So be it.
I just wanted to let TP-Link know that, after using TP-Link exclusively for many years in my home, I recently upgraded my network to a vendor other than TP-Link, solely because of the lack of this feature on Deco. My new solution (Ubiquiti) works great, even if it is more expensive and complicated (though more powerful as well). I really would have preferred to stay with TP-Link. Unfortunately TP-Link left me no choice but to switch vendors 😢. Too bad.
Ok I'm confused. X55 user here. I'm on firmware 1.6.7 as well and my lot devices are isolated from the main network. When I click on a lot device on the app, there's the menu "Device Isolation". I have it set to enabled. When clicked the option the message shows as follows:
When enabled, this device will be blocked from communicating with other devices on your home network to ensure the network security. While isolated, the device can still access the internet and communicate with other isolated devices.
Am I reading your post correctly or it's to a different matter. Pardon I'm still a newbie when it comes to this tech.
Yes, it is possible to isolate devices manually on the IoT network, but that should be done by default (or at least there should be an option to enforce it). I already have about 100 IoT devices (from maybe a dozen vendors) in the home we just bought and are remodeling, and I will add more over time. To be required to isolate each device manually would be a pain, and what if I miss one? Also, what about the time period between when the device is first connected and I get around to isolating it -- that opens up a security hole at least temporarily.
The Deco IoT network, as currently implemented, does solve one problem very nicely: the IoT WiFi can be limited to just 2.4GHz, which many IoT devices require. However, it completely ignores the serious security issue with IoT devices, which every security professional is concerned about. TP-Link is so close to getting it right (and thus having a feature that none of their competitors have in a consumer product), but for some reason TP-Link doesn't seem to think it's important. I raised this issue several years ago, but no fix seems to be in the works. Ultimately I gave up on TP-Link and tried a business-grade product from a different vendor 
Makes perfect sense, I see your point. 
You are right, ticking away 1 device after the other especially in the dozens is heavy tedious work when it can be done as a bulk or it's already enabled as a default option. Hopefully TP-LINK can do the right thing and make this option availabe.