@umm 

Not sure on the model of your router but try adjusting the wirleless settings. If one plug would go out that device may be suspect but if all smart devices are I would start at the router.

Sounds just like my smart plug

@umm thank you.  I appreciate the help.  Pretty much exactly not what I wanted to hear though.  (Not your fault).  I may try it soon.

@umm Same problem. Just got two Kasa Smart Plugs KP125 (firmware 1.0.3) and they keep disconnecting. They won't stay connected for even one day. They show up in the list of devices but they are grayed out with no on/off button visible. When I click on them I get the "Device Unreachable" saying that they may be "powered off or out of network range." I know they are in network range, and I am actually using a fairly recent and high end TP-Link router (Archer A20). If the plug is powered off it did it by itself. One thing... if I pull the plug out of the socket and then plug it back in it will usually start working again without having to go through setup again.

This is obviously an unworkable situation. If I go away for more than a day it will disconnect and I won't be able to turn it back on remotely. I refuse to reconfigure my router to accommodate these plugs. I will return them before I do that.

I have two other ones (both KP115) that work fine. They do not disconnect, so it's something about the KP125 plugs I have.

Hey TP-Link, I've seen people here and in other threads complain about this issue but you have never provided a reasonable solution (reconfig of router is NOT a solution). I think you should now before I return these and review them online. I am evaluating home security & smart home systems and TP-Link / Kasa will be disqualified over this.

@JohnB2 Since TP-Link will not respond with a solution, I will return my smart plugs, never to buy a TP-Link/Kasa product ever again.

@umm could you elaborate what you had to do to separate my 2.5ghz and my 5ghz network?

@Dcb15 

Different SID for the different radios.  I do not recall if I set up a second access point for that one.

@Dan_G That did not work for me. It continued to disconnect so I returned them. Very disappointing that TP-Link never responded here with a solution. I will not buy their products again.