Screencast and Wi-Fi can I be connected to Wi-Fi and still use screencast I'm trying to watch YouTube on my TV but I also connected my phone to the Wi-Fi I want to know whether or not is it possible to be connected to the Wi-Fi and still use screencast
Yes, in fact you have to be connected to the same Wi-Fi network that the Chromecast (or whatever device you're trying to cast to) is connected to, because casting works over Wi-Fi.

It may be that when you originally set up the Chromecast, you didn't connect it to your Wi-Fi network, but let it use its own Wi-Fi network. In this case, you'll first have to go into its settings and connect it to the same Wi-Fi network that you want the phone connected to.