User can use “set default” to set the current brightness as the power-on brightness.
User can also turn on “auto state saving” feature to let the bulb remember it's current brightness automatically,
so the power-on brightness will be the last saved brightness.
1) Your WiFi router is working and can connect to internet. Note: Yeelight LED bulb doesn't support 802.11ac (5G Hz), so please choose 2.4G when doing the initial connection.
2) Your smart phone can access the internet through your WiFi router.
3). Make sure Yeelight Application is installed properly on your smart phone. It needs Android 4.0 and above or iOS7 and above.
4). Make sure Yeelight LED bulb has not been connected before, otherwise, you need to follow the instruction to reset the bulb firstly and try again.
Although 4000K light shows a bit yellow, it's commonly called “white light” in LED industry.