Dreek, were you able to solve the problem? I'm having the same issue, all 5 plugs dropped off and I'm not able to reconnect. Reset the pug, changed my wifi name, reinstalled the app, no success. Any tipps?

Hey Kevin, HS100. The LED was red suddenly on all 5 devices.  After resetting, they flash green/orange, the app is able to connect the plug as wifi, but then in the next steps on Kasa does not find my home Wifi and therefore cannot add the devices to Kasa. Nothing had changed on my Wifi before this happened. Now aiming to reconnect them, I've changed my Wifi name, but the app doesn't find it. Made it invisible and manually typed in the name, no success either. reverted changes, still no success. I'm trying 1 plug at a time, but it is the same problem with all. 

without making further changes, today suddenly all plugs were being able to reconnect. 

and now all plugs show deep red again. Is there a new evening routine that disables all plugs? 

Hi, Kalinda80, that is weird, you can contact the tech support with the forum link attached to get some specific help.

https://www.tp-link.com/en/support/contact-technical-support/#E-mail-Support

PS: As far as I'm concerned, the network stability of main router's wifi is important. 

Absolutely weird. My network is stable (work from home). Day 3 now, clock turns 7pm, all plugs which have been green all day turn to red simultaneously. Right now, the only devices that use wifi are the plugs and my pc to write this message . I bet that tomorrow 8 am all will show green again, like today. The plugs seem to run on schedule though, yet I can't control them through Kasa obviously. Support was contacted on Day one, still no response.

I was right, 8:30 et voila, all plugs are green again. I'd wish support would respond, this can't stay that way.