0 tapped I have this too and 1 wrote in with details.
This is expected behavior, so there is no fix to wait for. Tapping I have this too still tells us how common the question is.
What is happening
iOS 27 replaces Wi-Fi Assist with Connectivity Assist, which uses cellular data alongside Wi-Fi when Wi-Fi is slow or unusable. Apple says it is on by default if you had Wi-Fi Assist on before updating, and that you may use more cellular data with it on. To turn it off, open Settings > Wi-Fi and scroll to the Connectivity Assist switch. If one network needs to stay on Wi-Fi, such as a home network with an ad blocker, Apple lets you turn it off for that network only. Apple's Connectivity Assist page has the details.
What readers are telling us
Cellular data shows not connected error
iPhone 15 on iOS 27.2, November 8
Short summaries of reader reports. We never publish names or a reader's exact words.
Have more detail?
A written report tells Apple and other owners what your device was doing when it happened.
History
- Nov 141 readers have asked about it so far.
Related problems
Know before you update.
Should I Update? tells you when a release is safe and what it fixed. Free, one email when it matters.