IOS update

Read the second half of the first link, or watch the second link:

"Update your iPhone, iPad, or iPod touch" click here --> https://support.apple.com/HT204204

Or this video:

"How to update your iPhone or iPad" click here --> https://youtu.be/csJAEyvvruY

The first document says:

"Update your device using your computer

If you can’t update wirelessly on your device, you can update manually using a computer that you trust. If your computer is using Personal Hotspot on the device that you’re updating, connect your computer to a different Wi-Fi or Ethernet network before you update.

1. On a Mac with macOS Catalina 10.15, open Finder. On a Mac with macOS Mojave 10.14 or earlier, or on a PC, open iTunes."

Go to a location with a stronger wifi signal (yours seems weak).

See recommendations here:

If your iPhone, iPad or iPod touch won’t update - Apple Support

Restart your phone and try again. - If you see an error when you update or restore your iPhone, iPad, or iPod - Apple Support

You do not need an Apple computer, any computer with iTunes will work just fine. See this Apple Support article.

Try updating through your computer.