It sounds strange, when you failed to control them via Alexa, could you control them remotely via kasa? If could, I suggest you contact with tplink support team,maybe they know what happened between...

I remembered that the plugs only support WEP/WPA/WPA2-PSK, don't support open wifi or WPA-Enterprise what you said.

yes it's OK to do that as long as the new HS100 is bound to the same cloud account.

It's impossible to setup WEP just for Guest network. You can use the other way you said.

Hi, does the RESET mean power on/off the router, or reset back to factory settings? If it's reset back to factory settings, make sure you see all the lights on and off except the power light, that...

How about the speed without the powerline adapters? The powerline adapters will be affected by other electrical appliance and the electrical environment，sometimes the speed may be not so good.