NVG589 DOCSIS 3.0?

Hi everyone. I have AT&T Uverse service. No FIOS just a copper line incoming from a telephone pole, so I assume DSL? Rather slow and crappy service, which it often is. One thing I read was to stop renting AT&T's equipment and buy much better stuff yourself. I am planning on replacing their crappy WI-FI router (Motorola VAP2500) with an Asus AC3200. Question: I've read that the modem should be DOCSIS 3.0. Is their modem (NVG589) DOCSIS 3.0? If not, can I replace it? Thanks