I’m having issues with my N900 properly updating with dyndns.org to keep my IP up to date. Prior to the N900, I was using a Netgear WNDR3700 with 0 issues. It seems that the N900 never truly updates with the service, and what I have to do is change the login info to dyndns.org within the router settings so that it says login failed, then re-enter the correct info and it will then save and update.
I have updated to the latest firmware for the N900 router; september 2012 update. And yet the problem persists! The router will not update IP information on DynDns.org. As the OP said, it has to be done manually for some reason. The issue is making me want to return this garbage of a router.
Also the manaul indicates that there is a separate option to utilize a western digital hosting service to allow remote access to the networked drive. Where is that option? it is not in any of the menu tabs.