Casting from mobile hotspot phone I'm on android 6.0.1. My main and only Internet is my phone. I don't have a router, Access Point, nor switch in my home. I use the mobile hotspot feature so other devices can connect to the Internet. My TV connects to the mobile hotspot as well. I am trying to cast from my phone to my TV but it doesn't seem to find it. Other devices have no problem. It's this at all possible to have mobile hotspot and be able to cast from the same device?
Its possible, it is much easier if you have two devices (e.g 2nd smartphone, tablet or PC)


Create a mobile hotpot AP using the secondary device. 
Once setup, connect the primary device (where you are going to setup chromecast) to the mobile hotspot AP and the TV
Setup the chromecast as normal with the primary device and since the setup is once off you don't necessarily need to use the secondary device after inital setup. The Chromecast stays configured to the hotspot's wifi until otherwise reconfigured.
The trick is to setup the Chromecast  and use the same WiFi settings when creating your hotspot. Chromecast doesn't look for a specific router as the source of the wifi signal. It just looks for hotspot name (SSID) and tries to connect using the stored encryption and password
The consequence is that you just use the same WiFi settings when configuring mobile hotspot for the primary device.


Acknowledgements


Chromecast Help Forum
Casting from Android device using mobile data?