Unable to copy photo from Iphone 11 Pro to portable hard disk drive

Hi All, I am trying to copy (backup) all my photos from my Iphone 11 Pro to a portable hard disk drive. Keep on getting error message "The requested value cannot be determined". For example there could be 1,000+ photos in a folder, but can only copy 100+ photos, then I copied in a batch, example 25 photos, but still cannot get to copy all into hard disk drive. from the 25 photos, maybe 1 or 2 successfully pasted into hard disk drive. for some it just cannot seemed to paste. The photos dated back to 2017 during the time was using Iphone 7. But even newer batch of photos (under current 11 Pro also cannot be copied and transferred). Pls help.