Mbps is only 3 when I'm paying for 300. Just set up, what do I do to fix this?

I just set up my modem and router, activated it, and testing my speeds. After multiple tests I'm getting roughly 3 mbps down and not even 1 up. My hardware is the Negear CM500 modem and the Netgear AC1200 router. I am paying for the 300 mbps plan, so I was extremely suprised to see only 3 mbps when testing. Hope someone can help, thank you.