I am running MSDOS 6.22. I think Modem7 told me that version 6.22 was good to 2-GB which must be FAT16B. Right now I have Debian 12.5.1 on a 64 GB SD card. The properties state the drive is UNIX file system. When you made your 200-MB file in your demonstration video, you were able to store files within the 200-MB file. So, did you have to format the file to FAT or FAT16 to receive the files from the DOS machines. Reason I ask is the EtherDFS required either a partition of FAT or FAT16 to mount and accept files from the DOS machines. I had a USB drive formatted to accept the files from say an XT type machine. It worked except of course for the access denied, which now can be fixed with the DEBUG correction.
NetDrive has a server mode and a disk image creation mode. If you create a disk image using NetDrive you specify the size and the filesystem (FAT12, FAT16 or FAT16B). NetDrive then produces a formatted image ready to be served to DOS.
See the full documentation here: link