@Solla-topee here is additional information

The AP is a MikroTik hAP ax3 running routerOS 7.7    I'm attaching the screen grab of the modes

All Kasa devices work on 2GHz N, but only 3 Kasa devices work on 2GHz AX

The authentication settings are as follows

I've also tried just enabling WPA2 PSK, but it makes no difference.

In the Kasa iOS app all it shows is that the devices are "Offline"

  @HomeLabCan 

Nice..  gear and organization.  If you are reusing the previous SSID / password.. maybe some devices are finnicky with the router change.. have you tried resetting and re-adding one or more problematic kasa device?

An unrelated thing.. for the devices that do work.. could you try locking / linking them to specific AP / nodes... and observe if they continue to operate okaya few weeks time.. and or after certain test scenarios.. router power off / on... power to certain switch segments off / on.   I have an Asus AiMesh setup and the kasa devices dont seem to work well if locked to a node..  I have to allow the router to manage the kasa devices.   My computing devices can be linked to specific nodes with no issues I'm aware of..

  @LearnTO 

Yes I tried to reset them, but even then they did not see the SSID in the iOS app.  I ended up using an old Asus RT-N16 and used the old SSID in 802.11n mode.  Not the ideal solution, but the switches are online.  Going to have to really think about the future direction of my home automation now.  Really bugs me that 3 of their devices have no issues at all.  Guess they don't want to support the older ones.

HomeLabCan wrote

  @LearnTO 

 

Yes I tried to reset them, but even then they did not see the SSID in the iOS app.  I ended up using an old Asus RT-N16 and used the old SSID in 802.11n mode.  Not the ideal solution, but the switches are online.  Going to have to really think about the future direction of my home automation now.  Really bugs me that 3 of their devices have no issues at all.  Guess they don't want to support the older ones.

@HomeLabCan 

Doesn't hurt to ask if you could have the problematic switches warranty replaced.   Otherwise, consider looking ahead for devices that support matter if replacing or adding new devices out of pocket.

Our home switches were due for replacement as our dimmers were not designed for LEDs.  Followed home automation and smart home tech for some time but did not want to be locked into costly or proprietary platforms.   Pulled the trigger over the 2021 holidays due to health needs.. and the benefits of automated, timed or flexible brightness and colour temps..  Went with Kasa as they complied with local regulations, affordable, readably available and although proprietary, they offered ways to connect to many other platforms, especially via Smartthings.   I'm in the tech field so use to bugs.. there's alot more bugs and issues that I anticipated.. However, from what I read this seems to be true for every vendor / platform even costlier ones.

Probably spent $4k on various smart home devices mostly TP Link Kasa. for in wall stuff and bulbs..  Ikea Tradfri for zigbee remotes, repeaters, linked via Smartthings.. and some Philips Hue.. (not yet installed...)  Fortunately, I have / or will recoup well over the costs by insalling the devices my own.

I've read some posts here where folks run across issues that are so easily resolved by a small investment in proper tools and reading or watching some examples.   No offense, but folks who cant be bothered to invest in proper tools or try to read or watch some instructions.. should just hire an electrician to do the job right.

  @HomeLabCan 

I have a similar setup, but with a mikrotik routerboard hap ax2.

I have created a virtual wireless interface and my old Kasa switch now see the wifi and can connect to it.

(Sorry for the image, if I write text in the post and got error message about external link)