I'm getting 1 Gbps from mine. If you don't, maybe try different cables.
I grounded it by attaching the ground wire to the grounding screw on the back of my UPS. Not all of them have one, but it's worth checking if yours does.
So, I actually have my cable modem on one small UPS - literally the only thing on that UPS. Then, I've got this protector between it and my router, which is on a second, larger UPS with everything else.
I could've used a surge protector instead of the first UPS, but the nice thing about a decent UPS (such as those with AVR) is that they protect your device from dirty power (high/low voltage and smaller power glitches). Since I put my cable modem on a UPS, I've noticed my cable modem rebooting far less often. Could be the reason.