Iphone Xr issues after upgrading to ios 14

1) Try and Force Restart your iPhone exactly as shown below and see whether that resolves the issue:

• Press and quickly release Volume UP button
• Press and quickly release Volume DOWN button
• Press and Hold the SIDE button until an Apple logo appears then release the Side button (Can take up to 20 seconds. DO NOT release Side Button when invited to Slide Power OFF). 

Axel F.

Check this: https://support.apple.com/en-us/HT201415

Reset your Network Settings.

Go to Settings > General > Reset > Reset Network Settings.

This also resets Wi-Fi networks and passwords, cellular settings, and VPN and APN settings that you've used before.

Your WiFi passwords will be deleted from iPhone/

1. Connect iPhone to computer and open iTunes
2. Make the backup
3. When it finished - enter the DFU mode:

https://youtu.be/U8ltCY8e5RY?t=219

When you will successfully enter this mode - iTunes will ask you to update the iPhone.

Update it

restore from your backup.

You can try to update the iOS again but in DFU mode and by cable with computer. (But first make the backup of your phone)

Do you know how to do this?

• If your iPhone, iPad, or iPod touch won't turn on or is frozen - Apple Support
• If you can't update or restore your iPhone, iPad, or iPod touch - Apple Support