My phone suddenly trun off

Re: " ... my phone is shut down and my Bluetooth disconnect and not connect again even I restart my phone and also sometime Wi-Fi disconnect and not connected when I shut down my phone, then start ..."

Apple support have troubleshooting articles online that may be helpful:

See how to: Resolve Wi-Fi and Bluetooth issues caused by wireless interference - Apple Support

Eg: says:

"Wireless interference can cause Wi-Fi and Bluetooth devices to disconnect or perform poorly, but you can take steps to reduce or overcome this". There's much more info. in the linked article above.

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If you still need help with connection to wi-fi:

See what to do:

If you can't connect to Wi-Fi on your iPhone or iPad - Apple Support

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If you still need help trouble-shooting a Blue tooth connection:

See what to do:

If a Bluetooth accessory won't connect to your iPhone or iPad - Apple Support