like the title says it works only on routers with old firmware and router-language set to english.

if you open the widget-package and look a the file "speedtouch.js" you will see this line: var url = "http://10.0.0.138/status.htm";
THIS file ony exists on routers with old firmware, on routers with the newer fw the adress is : http://10.0.0.138/cgi/status/no_wizard

maybe the developer can adapt his widget to work with old and new firmware.