D-Link have been quick to release new versions of the 1.33NA firmware recently, now they have released the final 1.33NA version.
In my experience it is one of the better versions of the 1.3x firmware family, here is the changelog:
- Fixed: Correct HNAP issue.
- Fixed: DNS relay issue ( WAN Slowdown )
- Added: Advanced DNS descriptions
Remember this cannot be downgraded by official means to anything pre-1.3x or other international firmwares, however you can always try the unofficial way.