Hotspot issue, connected, no internet I have an issue in my phone, and I lost hope I will find solution.

Phone:
* Xiaomi Redmi Note 4
Android Version:
* 7.0 NRD90M
MIUI Version: 
* MIUI Global 10.1
Kernel Version:
* 3.18.31-perf-g4339b70


The problem:
I share internet via hotspot and everyone can connect to it with any devices but when I connect my tablet (Galaxy tab) or my other phone (OP 5T) I got an exclamation mark next to my wifi and "connected, no internet".

I don't understand why. Can somebody help me what is the problem?
What is the thing that provides you internet ?

Wi-Fi or cellular data ?

if its wifi Android devices auto-disconnect from the wifi so they can host you Hotspot 

if its cellular data then i dunno !