The direct update is possible - however, you need to use the manual installation from the NAS Linux shell, together with a small workaround:
The update script on earlier firmware vesions can't handle firmware images larger than 99'999'999 bytes without some user intervention. Of course - ensue your have the essential data on a backup media, and disable any QPKG installed before. Remind you - some QPKG requirre an updte anyway.
Please do the manual update from the Linux shell - this is most safe for your NAS - and the only one allowing to copy-pater the transcript of the update process to the forum here in case, so we can see what might have failed.
Login on the NAS by SSH from your computer (Windows: PuTTY http://www.chiark.greenend.org.uk/~sgtatham/putty/
or OS X Terminal app: ä ssh admin@[NAS-IP-address]) using the admin credentials. Then you can enter the commands (the [~] shows just the currecnt directory, the # is the prompt.
The update process shown here http://wiki.qnap.com/wiki/Manually_Updating_Firmware
- just the 1-2-3 should be enough, add in between step two and three:
2. Create a link to the /mnt/update location:
# ln -sf /mnt/HDA_ROOT/update /mnt/update
# echo NIL > /mnt/update/newver
3. Run the update script:
# /etc/init.d/update.sh /mnt/HDA_ROOT/update/TS-xxxxxxxx.img
This is the only verbose update, permitting the community members to help in case something goes mad..