@David-W 

Hi David,
Generally, you can refer to the link below to troubleshoot if you fail to set up the Kasa device.
What should I do if I fail to configure the Kasa device?
 

If the problem remains, please help confirm the following information.
1. Please check the LED status on the HS100.
2. Who is your ISP? What's the model number of your router? Please check if your router has enabled MAC Filtering, Access Control, Firewall, etc. settings that may block the new device to connect.
3. Turn off the 5G Wi-Fi band on your router, ensure the Wi-Fi name and password has no special characters, and change the wireless security type to WPA-PSK or WPA2-PSK for a try.
4. Try to connect the HS100 to a hotspot Wi-Fi from your phone. If it can connect successfully, update the firmware to the latest one, and then reset it and check if it can connect to the router's Wi-Fi.

Best Regards

  @David-W 

Hi David,
I have not seen this error message before, to solve the problem, I'd like to escalate your case to the tech team, and they will help follow it up, if you are willing to do further analysis, please check your inbox and respond.    

Best Regards