The Yeelight Color Bulb II (YLDP06YL) does not automatically connect to wifi if, for example, I restart the wifi. I have to manually switch off the bulb from the power and then back on to reconnect.
Oh and one more thing, sometimes when I toggle the light with my Mi smart switch, only the Yeelight Color Bulb I are switched on/off, the Yeelight Color Bulb II does not. (it works with the second try with the Mi smart switch)