Stream Local Media to Chromecast Without Internet Connection
With Chromecast, streaming media to your TV has never been easier. The only downside is that it usually requires an internet connection to stream anything, even if you have media on your device. This workaround helps fix it.
Apps like Localcast can stream the media you have on your phone to Chromecast. The problem is that when internet access is available, it can still use mobile data to connect. To get around this, Reddit user Quaternions_FTW suggests creating a mobile hotspot with your phone and connecting the Chromecast as well as the device with the media you want to stream to the hotspot. You can turn off mobile data on your phone, which acts as a mobile hotspot, to prevent additional data usage.
While this might not be necessary for a Chromecast home device that has a regular Wi-Fi network to connect, it can be a lifesaver in places like a hotel where the only internet access is through your phone. Sending photos and especially video content to a TV can transfer large amounts of data very quickly.
LPT: Use Chromecast Without Internet / Mobile Data By Setting Up An Access Point Without Internet | Reddit