If the Homehub 5 works OK that means that there is no problem with your line.
You need to connect the Asus to your computer and go into the management pages and set it up with the information I already posted. Once you have done that plug it in to where the Homehub 5 is plugged in and it should connect.
are you sure yous asus has a modem built in and not just a router
edit from checking specs it says modem/router
from looking at back you are conencting to socket just above the power socket - sorry if obvious
Even if the dsl light is flashing, connect your router to a computer via ethernet and launch your web browser.
If you dont see the router set up page type 192.168.1.1 into your browser.
You should now see the routers set up screen and you can select your ISP bt