@Dimond 

Also, the access point is set to b/g not n.  It was a lot of trouble that it should not have been. 

@umm 

I am running into a similar issue with my KP125 plugs. I did the following and it fixed my issue:

1) Update the KP125 Firmware to 1.0.6

2) Connect a seperate router in bridge mode to your master modem 

3) Create a seperate 2.4 GHz network 

4) Connect the smart plug devices to that 2.4 GHz network

5) Disable 5 GHz network on the BRIDGE ROUTER (this way you will still have access to 5GHz from your main router)

This seemed to fix my issue but I'm not sure if it was just the firmware update or if removing Dual Band functionality from my router also had an impact.

Hope this helps. 

I will also note that TP-LINK / KASA need to be much more responsive in these forums if they expect to expand their customer base. 

  @umm 

I had one of my Kp125 plugs that would go local only a lot.  I use a tp-link mesh wireless with combined 2.4 and 5 ghz.  Support suggested that I use the guest network set for only 2.4 ghz.  That seems to be working very well.

  @umm  I had three smart plugs and they stayed connected without any issue for over a month.  Added a 4th, and now 2 or 3 disconnect at will, and reconnect at will, at random. Very frustrating.  All on are same network, have been checked for firmware updates, are about an equal distance from the router (less than 1200 sq ft radius & restarted after installation), and I have no issues with other IoT devices on this network (total of 8 devices). This is definitely a KASA issue and not router related.  The 'disconnected' plugs still work and seem to work on the schedule I selected just not changeable. It also doesn't matter where my phone is when I attempt to access (which shouldn't matter but was another thought I came across on a different troubleshooting place). KASA PLEASE FIX. I tried the blubs and those were an utter failure so I returned. I will not add any additional KASA products until the internal issues are resolved by the mfg.

  @JohnB2 I have same problem. Isolated/separate 2.4GHz only network, though it's still setup as a mesh across 3 access points (one per floor). 
 

I may try creating separate 2.4GHz SSIDs (one per access point) so no more mesh for Kasa devices, and then manually removing / re-adding each device, but that's a lot of work.  And not confident if it'll fix the problem. 
 

otherwise all devices are at latest firmware levels.
 

anybody else try going old-school and turn off Wi-Fi mesh?

  @Meekers I returned mine. You shouldn't have to reconfig your router or turn off mesh to get a simple plug to work correctly. And there is a complete lack of support from TP-Link, which is really poor. I will never buy another one of their products, and that includes upgrading my router soon. I'll check out Netgear or someone else.

Meekers wrote

  @JohnB2 I have same problem. Isolated/separate 2.4GHz only network, though it's still setup as a mesh across 3 access points (one per floor). 
 

I may try creating separate 2.4GHz SSIDs (one per access point) so no more mesh for Kasa devices, and then manually removing / re-adding each device, but that's a lot of work.  And not confident if it'll fix the problem. 
 

otherwise all devices are at latest firmware levels.
 

anybody else try going old-school and turn off Wi-Fi mesh?