why it shows that my phone isnt connected by internet while updating

Hi nouraalenezi

welcome to the Apple (user-to-user) Community.

Re: Why it shows that my phone isn’t connected by internet while updating but it’s already connected

Wondering how strong your internet connection may be.

Seems you need to have your phone plugged into power, and have a strong wi-fi signal (or some phones can use cellular) / connection while updating.

Else: Updating an iPhone using a computer is a good method.

Apple support's articles (links below) may be helpful:

Update your iPhone or iPad - Apple Support

What to do: If your iPhone or iPad won't update - Apple Support

All the best :-)