Internet speed problem ...

Upgraded to the Cox Panoramic Wifi Gateway Brand: ARRIS Model: TG4482A with the 550mbps internet plan.

From Cox's own website (Speed Test) ... this is what I'm getting:  

Ping: 14

Download: 45.5Mbps

Jitter: 3

Upload: 10.8Mbps

Can anyone explain why the sudden speed drop?

-Colton