If your home router has a Dynamic DNS feature and it suddenly does not work anymore with DynDNS… don’t despair. The guys at DynDNS have decided to discontinue service to older clients. You can read the small print here.
The bad part is you don’t get any notification. Their server simply returns a “Successful update” error code. You might smell something that is fishy because it also reports that your new IP is 127.0.0.1. But your real IP in the database remains unchanged.
The good news, though, is that your account is not blocked, too. You can update the DNS manually or from a desktop client. Check the router vendor site for a firmware upgrade. If there is no such upgrade, there’s not too much to do, except use the desktop client and choose a different dynamic DNS or router provider.