Bulb disconnections very often

Hi,
I have 5 bulbs:

  • 2 Mi LED Smart Bulb (White and color)
  • 2 Yeelight LED Bulb (color)
  • 1 yeelink.light.color1

The 4 firsts always get disconnected after a some time (days(s)), while the last one remains connected.
They are all connected to same wifi rooter (google wifi). Rebooting the router doesnt help, I need to power cycle the bulbs to have them back online.

What’s wrong?
My MI ID is 1645261696

Regards,
Pierre