The first time I loaded 1.25NA, the router still showed the old version of the firmware (1.22) after rebooting.
So, I loaded the new firmware a second time, and it finally worked. My router now shows firmware version 1.25NA. All settings reverted to factory defaults, so make sure you know your configuration settings before updating.
I am hoping this new firmware makes the DIR-628 router more reliable. I bought this router 2 weeks ago to replace an older one that died. The new router tends to stop working about every 48 hours. Rebooting it gets everything working again. But it would be nice if it kept working without needing frequent reboots!