Connecting to a chromecast messes with the Wifi upload
When the chromecast is connected we are unable to have wifi sharing enabled at the same time. The least we should do is turn off wifi sharing when the chromecast is being connected.
Ideally If the user has wifi sharing enabled, we should ask if he would like to disconnect wifi and start casting. There are scenarios where he might upload a video currently and doesn't want that/ doesn't realize that he kills that connection by casting.