FiveNetwork connection not working with router

I have just bought a new Asus RT-N12 D1 router and trying to configure it. My ISP Five network support PPPOE connection and i have a user name and password. when i use the same use username and password to connect directly to my laptop(without router), every thing works fine, but when i tried to configure router and use same username and password its not connecting and saying "either username or password are incorrect". did't understand why username and password is not working on router while same username and password is working fine when i directly connect through laptop. is there any thing extra i need to configure on router. any help will be appreciated. Five neworks guys are not at all helping me.

Enable MAC cloning option.

If your router doesn't provide this service directly then read this

Source

If your router doesn't provide this service directly then read this

Source