Do a 30/30/30 reset and then use the default values -- and double check that they are correct, some of those have the default password printed on the bottom.
Here is the 30/30/30 reset procedure: With the unit powered on, press and hold the reset button on back of unit for 30 seconds
Without releasing the reset button, unplug the unit and hold reset for another 30 seconds
Plug the unit back in STILL holding the reset button a final 30 seconds .
If that does not work you will have to exchange your unit with your ISP.