RN104 backup getting error "operation not supported"

Hello

I have an ancient RN104 holding four 4TB drives.
     It is 60% full and consists of seven sub-shares.
     I want to backup one of the sub-shares that contains about 1TB per Win11 Explorer

I plugged a 2TB drive in the rear port
I started a FULL backup of that sub-share

Here is the top of the LOG file

   Why does the backup stop on the .AVI and .MP4 file types?

Backup Job Name: BackupTo2TB
Backup Job Type: Full
Protocol: local
Backup Source: [Backup]/Family Videos & Photos
Backup Destination: [USB Back Top]/
Backup Start Time: Tue Feb 07 2023 4:31:58 PM
Backup Finish Time: Tue Feb 07 2023 9:02:25 PM
Backup Status: Fail: Failure during copy.

Cannot write file '_Mom/Mom_MASTERS/Mom03_Master_20090801_PhotoReview.avi' (error: Operation not supported)!
Failed to copy file '/media/USB_HDD_6/_Mom/Mom_MASTERS/Mom03_Master_20090801_PhotoReview.avi' (error: Operation not supported)!
Cannot write file '_Mom/_Mom-FINISHED/MPEG4 1920x1080/Mom_Chapter2.mp4' (error: Operation not supported)!
Failed to copy file '/media/USB_HDD_6/_Mom/_Mom-FINISHED/MPEG4 1920x1080/Mom_Chapter2.mp4' (error: Operation not supported)!
Cannot write file '_Mom/_Mom-FINISHED/MPEG4 1920x1080/Mom_Chapter4.mp4' (error: Operation not supported)!
Failed to copy file '/media/USB_HDD_6/_Mom/_Mom-FINISHED/MPEG4 1920x1080/Mom_Chapter4.mp4' (error: Operation not supported)!

Copy Folder 1972