You’re right, with a classic RGB LED without any additional logic you can only display three modes (+ LED off). So you could either build an additional logic for white (= WLAN) that activates all three colors (that should result in something “whiteish”) or you use an RGBW LED (with an additional pin for white). For example, see this thread: https://forum.arylic.com/t/black-red-with-2-1amp-inside/902