If you are new to this and don’t about the issue, then you must read this part. Otherwise, you can skip it. The error called “[link|https://fixyourandroid.com/fix/mobile-network-state-disconnected/|Mobile Network State Disconnected]” it’s about the signal issue of an Android phone, often it happens because of the network sim if you have an only 3G sim and the phone is trying to connect to the 4G network.
Diagnose the mobile network state disconnected Error
* Method 1: Restart the device
* Method 2: Check for Networks
* Method 3: Check For the Reception
* Method 4: Check router settings
* How to fix mobile network state disconnected Error?
* Method 1: Change Mobile Network mode(3G/4G)
* Method 2: Reset Network(Sprint, AT & T)
* Method 3: Deactivate The WIFI Connection
* Method 4: Reset The APN Settings
Source: [link|https://fixyourandroid.com/fix/mobile-network-state-disconnected/|https://fixyourandroid.com/fix/mobile-network-state-disconnected/]