Years of frustration and HOURS wasted!
Sometimes my TV connects immediately, via Google Home or even screen mirroring directly via YouTube or whatever is on my Android.
Sometimes it just can't find device (TV) EVEN after rebooting TV, or Chromecast, or restarting hotspot.
It has a mind of its own and I can spend an hour going through all the connections etc before it decides to work.
I use just one Android phone after initial setup with 2 phones but it's just a matter of luck to achieve a connection.
Thanks for reaching out and I'm sorry to hear that you're having a connectivity issue with your Chromecast using a mobile hotspot.
Give these steps a try:
If all troubleshooting steps fail to resolve the issue, please switch to a stable Wi-Fi connection as it is recommended over a hotspot setup for the best performance.