It would not be the first time that an iOS update has caused an issue in the iPhone, but Apple has been always ready for such instances, providing a quick resolution for them. Apple pushed an update for iOS in July with version 14.7.1. Although there were not many issues with the update for global users, there has been a large chunk of iPhone users that have been facing issues with cellular connectivity. The major issues that the update resolved were the security issue with arbitrary code which could be executed with kernel privileges and issues that prevented Apple Watch from unlocking the iPhone for mask-wearing users.
Although both the issues were resolved for everyone facing it, it created a new issue where iPhone users lost cellular connectivity after installing the update. The issue was raised by many users on the Apple Forum and other platforms with the initial post related to the problem spotted a week back. The users have already tried resetting the phone, resetting the network settings, and using a new sim card. Although, the issue seems to persist in the smartphone.
As per a support document provided by Apple, users have to make sure that they are in an area which the cellular provider covers and should attempt a carrier update setting update. It can be done from Settings>>General>>About. If there is an update, it will show and can be downloaded. In most cases, the issue has been resolved and Apple is already working on a new fix for users whose iPhone is still not working.