Please read the .pdf file that comes with the .28 upgrade file. The .28 upgrade is non-standard and you will need a USB pen drive. It will reset the N2200Plus back to the factory settings, although the data was preserved on the raid array.
The .39 firmware fixed a problem I was having connecting a Mac OSX 10.6.7 client to a shared folder. Two sub-folders gave permission errors even though they had the same ACL as the parent directory.
My thanks to Thecus Europe Tech Support for helping me with this.