Wifi
When the phone is locked, the WiFi will turn off
When the phone is locked, the WiFi will turn off
That's expected behavior. It should reconnect when you wake up the screen. It should remain connected if your phone is plugged in to power, too.
~Lyssa
You cannot prevent it from doing so. It's built in to iOS.
You can leave feedback for Apple here: Feedback - iPhone - Apple
~Lyssa
Which iPhone do you have?
~Lyssa
Okay - here's a document with some suggestions for making sure Siri works properly.
Get help with Siri on your iPhone, iPad, or iPod touch - Apple Support
Specifically, the phone needs to be face up in order for "Hey Siri" to work.
~Lyssa
It shouldn’t.
How to fix?
I don't want when the phone is switched off disconnected Wi-Fi. Because I can't say «hi to Siri»because she only works with the Internet. How to disable it?
You see, when I turn off the phone, the WiFI turns Off, when I say "hi Siri", then write "need a WiFI connection" and I have to unlock the phone
iPhone 7
I want the WiFi not to turn off when the phone is locked.
You need to leave your phone plugged in to power for the wifi to stay on. There is no way around this.
"Hey Siri" should work at any time with the iPhone 6s and later according to here: Use Siri on your iPhone, iPad, or iPod touch - Apple Support
If you have an older phone, it needs to be plugged in for "Hey Siri" to work.
~Lyssa
Wifi