@dlwhite66 Same happened with me, came here to find out more info.  Sporadically a few devices (in a group) show up.

  @dlwhite66 same with me too.

  @jjhung88 Yes.  Same here at about 10PM Eastern time.  All linkages to Alexa service down too.  

  @Bob_Smith I have intermittent use via google home. mostly it shows offline and sometime online. just deleted all data and cache, uninstalled and reinstalled. done that twice but still no go.

  @jjhung88 

I am not going to mess with anything for now.  Rebooted my router and that did nothign of course.

There is obviously a systemic problem here with the service.  Hopefully TP-Link / Kasa can get this figured out and magically tomorrow morning will wake up and it will be restored like it never happened.

This is the reason why I never put anything mission critical on these smart devices (door locks / garage doors, etc).........

  @Bob_Smith and they are back. Did nothing but wait. Would be nice if the system status reflected this temporary outage/update/whatever. 

Same thing.  I waited overnight, and when I got up, all my devices were back & functional, except one 3-way circuit.  Of courses the switches (primary = connected to power, & secondary = connect to house device) worked, but the app does not show the primary switch.

I have tried over five times to add the primary switch, & every time I get past the SSID/password page & switch the phone to the SSID, the phone waits a couple minutes for the connection to be established, & then errors out.  Doing a 10-second full reset & trying again does not help.  Thinking it might be the fault of the primary switch, I reset the secondary switch & tried to add it.  This worked; see the reply below.

It's clear that the primary switch makes the WiFi connection, because the WiFi lights steady green for a few seconds, & then goes out.  Further, the WiFi router shows a good WiFi connection & the IP address of the switch.  However, Kasa is unable to add the device to my app.

It would be nice to hear from Kasa about this problem.

Edit:  I just added a brand-new, never-used HS103 plug, & that worked.

This time I did a full (10-second) reset of the secondary switch, & successfully added it. I then held the switch on the primary switch for 5 seconds to force it into passive mode. Everything is working again.

Note that this primary switch is the only HS210 switch I have ever seen that has the traveler screws on the bottom of the switch.  If this switch is junk or has failed, let me know & I will replace & junk it.

Edit: So that the active (connected to WiFi) switch is primary (connect to power), I ended up swapping the installation of the two switches.

This brings me to another question:  After I have installed two HS210 switches in a 3-way circuit, is there an easy way (without removing the wall faceplates to use a voltage probe) to tell which switch is wired to power & which switch is wired to a house device?

I can easily tell which switch is active (connected to WiFi) & which is passive (hidden from the app) by briefly pressing the right-hand button.