are you doing a manual backup or auto backup?
How much data are you attempting to backup?
How much free storage space do you have in the iPhone?
Can you manually transfer the picture/videos?
What happens when you try manual transfers in smaller chunks?
The way iOS works when transferring date to the wireless drive is that the date is copied to the clip board and then transferred to the wireless drive. Once the transfer is complete the clipboard is cleared. If the total amount of data being copied exceeds the available storage on the iOS device it can sometimes cause issues. If this is what is causing the issue if we manually back up the data going forward auto backup will be incremental so the issue should not occur as often.
If you have plenty of available storage since the app is crashing you can share the iOS crash logs and we can see if we can see what may be causing the crash.
how to get iOS crash logs
