@Enigma22 

Have you tried to disable 2.4Ghz SSID? Maybe it is 2.4Ghz wireless channel issue. 5Ghz SSID should not have the problem.

Also you may double confirm if this EAP is "Connected" status on the controller Devices list.

Thank you, I'll try to see if it ll work for 5Ghz.

About the device is connected or not, it is also i have clients connected, the problem is not for all clients but just some.

My 1st phone is connected but not the 2d.

Ps : I'am using captive portal for connection if it can help to find a solution.

  @Somnus I tryed to disable 2.4Ghz, it only reduced the number of connected clients since those who can only connect in 2Ghz can no longer connect (i think)  but that did not solve the problem

  @Enigma22 

"Unable to get IP" also means this wifi may not be connected to your network correctly.

Maybe one of your EAP has Ethernet connection issue to your switch?

I have the same problem with C210.

Resetting cam (and reinstalling app) and disabling 5GHz or data plan won't help.

The only way to get it to work is by changing the wifi password (and reset the cam, so you can setup the new password).

It's been 3 weeks, and has observed intermittence disconnection (router restarted). Whenener it restarted, it will failed to connect again. I will have to update the wifi password to something else first and then change back to the original password for it to work. This work consistently.

TP will need to drill this down. It's obviously a firmware issue. No other appliances in my home have the same issue.