Hello DardZyla,
Thank you for using Apple Support Communities!
We understand from your post that you have not been able to install the iOS 14 update because you are receiving an error saying, "OS 14 failed verification because you are no longer connected to the Internet." In a situation like this first restart your iPhone.
Restart your iPhone - Apple Support
If the issue persists, then remove and download the update again using the steps from this article:
If your iPhone, iPad or iPod touch won’t update - Apple Support
"Remove and download the update again
If you still can't install the latest version of iOS or iPadOS, try downloading the update again:
- Go to Settings > General > [Device name] Storage.
- Find the update in the list of apps.
- Tap the update, then tap Delete Update.
- Go to Settings > General > Software Update and download the latest update.
If you don’t see the update in the list of apps or if the issue happens again, you need to update your device with your computer using Finder or iTunes."
Best Regards.