Update

Bostontomm Said:

"Update: Cannot update (greyed) it’s something about operating system and need WiFi to download but nothing works"

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Use a Computer and Ethernet:

Start with attempting an update through use of a computer. But this time, user Ethernet.  Go Here: Update your iPhone Using a Computer - User Tip. On the computer, you would connect it through Ethernet, going directly into your router. For a Mac (or PC) that does not have Ethernet, this would be the adapter to use: Belkin USB-C to Gigabit Ethernet Adapter - Apple

Start here: https://support.apple.com/en-us/HT204204

and see if this helps: https://support.apple.com/en-us/HT201263