@TP-Link Hi, it an Asus Bluecave AC2600. Yes the issue started as soon as i tried to add the KP303 to the Kasa app - specifically when i tried to add the device to the 2.4Ghz network.

@WhiteRedHat 

Yes, I have the same issue and sam response. Try many time. Still doesn't works. Anyone can help?

@MikeP Hi Mike, After i power cycle the router the router remains powered on and the 2.4Ghz wifi networks appear briefly before they all disappear. When i unplug the KP303 and then power cyclle the router the issue still remains. I turned off the phone, rebooted it and watched the wifi behaviour from another device (iPad) and it's the same - as soon as i try to add the KP303 it takes down both the 2.4Ghz and 5Ghz networks.

The 5Ghz network recovers but devices can't connect to it.I appreciate your thoughts on something else being the issue, but the only change that triggers this issue is adding the KP303 - therefore it is the root cause.

I also took the following action:

1. Factory reset the router

2. Created 1x 5Ghz main network and 3x 2.4Ghz networks (1 main and 2 guest - the guest networks only have internet access, no intranet)

3. I added all non smart home devices on their respective main networks networks

4. Let this config sit for 2 hours - no problems; strong signal everything working.

5. I added all smart home devices (3x TP Link HS100s, 2x Ring cams and 3x Echos) to the 1st 2.4Ghz guest wifi network

6. Let this config sit for 2 hours - no problems; strong signal everything working.

7. Attempted to add the KP303 to the 2nd 2.4Ghz network. Managed to step through the process in the app and as soon as it showed success - pop, all wifi networks disappeared from almost all devices. The 5Hz network re-appeared but most devices could reconnect to it; iPad and Android phone tried but failed. However my desktop PC connected via an Intel wifi card remained on the network..

8. I powered cycled the router; wifi networks briefly re-appear but only the 5Ghz stays online and again most devices can't connect to it except my PC with Intel AX200 wifi card.

9. I connected my laptop via ethernet cable to the router and changed the 2nd guest wifi network password (the one the KP303 is meant to be connected to) and the wifi networks come back online - presumably because it's blocking the KP303 from accessing the network.

10. I left the left the power strip on, but disconnected from the main or guest 2.4 Ghz networks/unconfigured in the app and the router/wifi networks are behaving normally - i.e. are working.

So i've managed to isolate that the KP303 is triggering the behaviour; somehow as it's being added, or is added to the network it is triggering the issue as well as leaving lasting disruption. I wonder if the PC is retaining its wifi connection because the connection in contant use/always on, and doesn't need to drop off then re-connect to save battery (like a phone, iPad, battery powered cameras etc..). But somehow the KP303 is disrupting the routers ability to allow devices what periodically/frequently drop off then reconnect to save power from re-connecting at all.

Note that the older TPLink devices had no impact and are working fine until the newer one is added to the network - what software/hardware changes have you enacted in terms of wifi connectivity in the KP303?