Why is my iPhone searching and not connecting to my network?

Searching for the range of the mobile network, see this Apple article:

If you see No Service or Searching on your iPhone or iPad

If you see No Service or Searching on your iPhone or iPad - Apple Support

👉 If you still don't have a 'service' after that, see -> iPhone 7 Repair Program for "No Service" Issues

iPhone 7 Repair Program for "No Service" Issues - Apple Support

In addition to Raicya’s answers, consider the possibility that your carrier has a local outage. Ask them and also check up on them here→Down Detector - Crowdsourced Outage Check