I experienced the same issue after updating to iOS 18 beta 5, where mobile data stopped working. However, I manually set the cellular data network from other phone with same provider , and voilà, it started working again.
Seyoum
Users receive reputation points by contributing quality content to the forums.
Posts include post and replies published on the forums.
Post authors can mark replies as Accepted to indicate successful solutions.
Apple Developer Forums admins can mark replies as Apple Recommended to indicate an approved solution