I have a new motorola sbg6580 and its blocking out my Mybooklive, i can log in the mbl webpage and drag and drop files, but smartware cant detect the drive anymore.
You may check if there is firewall active in your new router that might be interfering. You may also try uinstalling SmartWare, restart your computer and install its latest version.
Make sure uPnP is enabled on the router. This is the technology smartware uses to detect the My Book Live.