@A_Miller 

Blinking Green indicates that the cameras are connected to the internet.  Solid indicates internet and cloud so that would match up with what you are seeing.   When you state you try removing them and re-adding them how are you doing that?  swiping left to remove and then tapping the "+" to readd them?  Or are you resetting them to factory and trying going through the whole setup and linking process?

Additionally have you tried to sign out of the app and back in?  

The other thing you can do and will likely help is change the DNS servers of your network.  I understand that some devices are working but other are not but still changing the DNS can help resolve this.  We recommend Google's 8.8.8.8 and 8.8.4.4.

  @Carl 

As stated in my original post I have already changed my DNS to 8.8.8.8 and 8.8.4.4, that has not made any change. 

I have removed the cameras from the Kasa app by long pressing on the device and then pressing the remove button that appears on the right side of the screen. I then proceeded to reset them to factory before trying to use the + button to attempt to re add them. Again, the cameras get to the stage in which they blink green and do not progress further. 

I have tried logging out of the app, closing the app, relaunching the app, logging back into the app, then attempting the process and the result is the same. Both cameras blink green and never complete the adding process. 

  @A_Miller 

I appolgoze i did misread your orginal post and missed the section about the DNS.  What we would need to do is have engineering consulted.  I would need your TP-Link ID email address to do this.  Please DM me that infromation or email at ussupportteam@tp-link.com so i can forward that information over and see what we can do. 

  @Carl 

I have sent you the requested information as well as some other information I suspect may be helpful. If you need anything more to further troubleshoot this issue please let me know what I can do to help. Thank you. 

  @A_Miller 

Any updates/fixes for this issue?  I'm seeing the exact same behavior with two camera's (KC410S and KC420WS).  Flashing green LED, showing in the client list in the wi-fi router, all other devices have internet, but these camera's will not connect to cloud and show as offline in the mobile app.

Thanks in advance

  @ghostryder 

Several days ago I provided the additional information that @Carl requested as well as some additional information about one of the cameras in question such as serial number and MAC address and also provided my router and modem model information. I have gotten no response so far since then. 

  @A_Miller 

Our team doesn't work on Weekends so I wasn't able to forward the infromation you emailed to us until yesterday.  I got a response today and the engineers are investigating.  They have a few follow up questions they would like to get answeres on.  Please check the two questions below.

1. Can you use a PC, connected to the same network and attempt to ping the camera's IP address and share the results?

2. Do you have the ability to configure a phone into HotSpot mode and configure the camera to connect to that network to see if you can reproduce the concern?  It may require a 2nd control device like another phone or tablet to do.