Iphone 7 model A1660

See this support article:--> If you see No Service or Searching on your iPhone or iPad - Apple Support

If the issue persists, see if your device is eligible for this repair program:--> iPhone 7 Repair Program for "No Service" Issues - Apple Support

Regards

Giulio

Try to connect to WiFi and have the phone plugged in. From the looks of it, you are using a hotspot which isn't reliable enough in most places to use for a software update.

Sorry I didn't notice (in your picture) that you are using a personal hotspot.

To perform an update procedure, a wifi connection with internet access, is mandatory.

If you don't have an wifi network, "borrow" one from your friends or ask for help at an Apple Store or Authorized Service Provider.

Regards

Giulio