Yash_01 Said:
"Still facing same problem"
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Use 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