when i was transferring data/apps from my old iphone 7 to new iphone 12, it appears to be in stuck mode.

So Quickstart has 'finished' but there are still apps that haven't downloaded?

I've seen this myself a couple of times..

I tried going to Settings > App Store and toggling the switches for Automatic Downloads

Then doing a force restart

• Press and quickly release the Volume Up button. Press and quickly release the Volume Down button. Then press and hold the Side button until you see the Apple logo.

also, here is a support article

If you can’t download or update apps on your iPhone or iPad - Apple Support

Tried several times to transfer data from iPhone 7plus to iPhone 12, but after some time it says “ unable to setup, reset’

What can I do?

I have been trying to transfer data from my iPhone 8 to my new Phone SE and it is delivering the message "reconnecting"

for hours. What is the problem?

How long should the data transfer take?