On the initial setup connect the isp modem to the wan port of the Netduma and then use an ethernet cable to connect from your PC/Laptop directly into one of the ports on the Netduma router. on a google chrome or firefox browser type in dumaos/ and it should take you to the setup page.
The setup will not work via Wifi, I believe that they are working on a fix for that right now.
For the people that are not getting internet connection after performing the setup, make sure that you are not connected via wifi, sometimes you may think that you are connected via ethernet but wifi might be prioritised.