Just to add ours to the pile of growing issues with 14.2 - this one on iPhone7
The initial problem she found was that the mobile cellular and data would not engage as it had an error saying the update had not been verified and could not connect to the internet (although was on wifi).
"iOS 14.2 failed verification because you are no longer connected to the internet"
We reinstalled fresh updates from the phone as well as iTunes – successfully being able to look at what iOs we were running and the phone confirmed 14.2 was installed correctly and fully – but we still could not connect to mobile cellular or data. We then subsequently decided to do a factory reset and reinstall from scratch.
The phone now is stuck after going through most of the welcome process with an error message: "Unable to activate" and "an update is required to activate your iPhone." underneath that.
This occurs after connecting to wifi in the welcome process.
We took the phone into an authorised Apple repairman here and has said this is one of SEVERAL phones to now come in with this problem, saying there is nothing he can do unless Apple posts a software fix to the update.