Yeelight ceiling light does'nt reconnect to Wifi

Sometimes after I restart my WiFi router, not all ceiling lights are able to reconnect again. In this case I must do a manualy on/off on the wall switch. What cause this issue and why it is not trying to reconnect again after a while?

It’s because it takes a few minutes for the devices to reconnect to the WiFi network.

In last case I waited half day, so the problem is not this.

I have several lights and sometimes when I have to switch off the power, some of the lights don’t reconnect. Usually one. What I do then is turn off the light, and leave it for 15-20 minutes. Then when I turn it back on, it connects just fine.