It demands that make certain thaty phone and my television are connected to the same wi-fi, however, I don't use wifi( persay) because I am on mobile data with my provider, and if I turn ony wi-fi... It turns my mobile data off. I try to use it by putting my tv on mobile hotspot which is turned off when wi-fi is turned on. WTF!!!
The Chromecast and the device used to control it or cast to it, must be on the same network. If you have a 2nd phone or iPad/ tablet you can use following workaround:
The best would probably be to get a 4G router and 2nd SIM? If internet to your place by cable (DSL, coax, fiber) is not an option I mean.
Or you could get an HDMI adapter for your phone to show its' picture on your TV, not using the Chromecast?