Welcome to the forums.
Sorry to hear you're having trouble. Please take a few moments to review the Forum Rules, conveniently linked at the top of every page in red, and pay particular attention to the section on how to formulate a useful problem report, especially including a detailed description of your hardware. This forum doesn't specialize in transforming your Asustor hardware to TrueNAS, rather, it is aimed at building NAS units out of standard Intel server hardware. Without some specific description of what kind of hardware is in your Asustor, including ethernet chipsets, it is unlikely you will get any help. I doubt anyone here has a unit like yours.
As a result, it is likely the responses will tend to be random guesses rather than anything useful.