Use APKPure App
Get Grundig Wifi RGB Bulb old version APK for Android
This app can control your device and bulb via wi-fi .
This app can control your device and bulb via wi-fi to realize such function on bulb:change color(RGBW), color tempreture(2700K-6000K), lightness. Even you‘re outside， you cloud use the remote function to do your remote control.