file size limits on extfat?

Because it has 4GB file size limitation

http://www.on-time.com/rtos-32-docs/rtfiles-32/programming-manual/exfat/benefits-of-the-file-system.htm

You should check NAS device permissions. This seems to be a permission issue due to which you're not able to copy the file.

ExtFAT is not a file file system.

FAT is.

exFAT is.

Ext2/3/4 is.

Which one you are using will determine your problem.

Details on Windows file systems can be found here:
http://www.ntfs.com/ntfs_vs_fat.htm

You might also have quotas enabled if the the file system is capable of handling a large file.

It's also possible your NAS uses a proprietary file system that doesn't support large files.  Could help to know WHAT NAS you're using.

The NAS is labled Purex on the box. The device itself and all documentation are devoid of names and identifiers. It appears to be a generic box that vendors can re-label.

exFat is documented to support terabyte-plus files. takecoffe, that link you posted says, "exFAT overcomes the 4G file size limitation of FAT." exFAT file size is 16 exabytes (http://www.tech-recipes.com/rx/2801/exfat_versus_fat32_versus_ntfs)

In fact I was able to copy these large files if mounted from Linux, so I'm not sure where the limitation is. However, the NAS has proven inadaquate. It seems to drop network connection and users can only open large files (e.g. 1MB) only about 20% of the time. When restoring to the NAS from a backup it failed to copy many files. I think this device is simply not business quality. It is going back today.

I'll leave this open today for any last comments

leew: I'm beginning to come to the same conclusion -- waste of money.