@ANVW 

Okay, I understand that after disabling the Guest Wi-Fi on your Deco Mesh system, your IoT devices started behaving abnormally, but when you re-enabled the Guest Wi-Fi, the IoT devices worked properly again. You're concerned that the firmware may not be handling the Guest and IoT networks correctly.

Here are some steps you can try to address connectivity issues with IoT devices on your Deco Mesh:

If all devices are unable to connect to the Deco Wi-Fi network:
1) Open the Deco app and go to MORE > Wi-Fi settings. Double-check your SSID and password, ensuring there are no extra spaces at the beginning or end of the password.
2) Navigate to MORE > ECO Mode (if available) and make sure ECO Mode is turned off.
3) Reboot the main Deco unit.

If only specific devices (such as IoT devices) are having trouble connecting:
1) In the Deco app, go to MORE > Access Control (Allow List or Block List) and check if the device is mistakenly blocked.
2) Go to MORE > Advanced > Fast Roaming and disable Fast Roaming.
3) In Client List (offline client list), find the specific device (if it exists) and delete it. This will remove any connection preference settings that might be causing the issue.
4) Try changing the main network encryption method to WPA2/WPA-PSK or "none" under Wi-Fi settings or Guest Network, then reconnect the device.
5) Update the Wi-Fi driver or firmware of the client device if possible.

For IoT devices that only support 2.4GHz and are configured via a phone app:
1) Enable the IoT Network in the Deco app (MORE > IoT network) and connect your IoT device to this network. If your Deco model does not support the IoT network, you can temporarily turn off the 5GHz network to help with configuration, and re-enable it afterward.
2) Switch the Wi-Fi Backhaul Mode to 'High Capacity' to improve 2.4GHz performance.
3) Double-check your Wi-Fi SSID and password, and avoid using special characters such as spaces, #, $, /, %, *, @, &, brackets, or non-English characters.

If you continue to experience issues, please ensure your Deco system is updated to the latest firmware. For more detailed troubleshooting, you can refer to this FAQ: https://www.tp-link.com/support/faq/2718/

Notes:
• The IoT network and main network have different network names but are on the same local area network, so devices can communicate with each other.
• If you do not see the IoT Network option, make sure all Deco units are updated. If the option is still missing, your model may not support this feature.

If the problem persists after following these steps, please let us know more details about your Deco model and the specific IoT devices affected, so we can further assist you.