Why does my iPad keep switching to Cellular when I'm connected to a Wi-Fi network?

If your iPad keeps switching to a cellular connection even when you're using a Wi-Fi network it is probably because you have Wi-Fi Assist enabled. Wi-Fi Assist is a feature found in iOS 9 that allows your device to switch to a cellular network when your Wi-Fi network is poor. This is a great feature for when you're using a public Wi-Fi network or carrier/cable provider Wi-Fi hotspot. You can disable Wi-Fi Assist by navigating to Settings > Cellular and scrolling down until you see the Wi-Fi Assist slider. Tap the slider so it is WHITE / OFF.