Upgraded to Gigablast with new modem, not getting close to advertised speed?

From Fairfax, VA here, I was recently a part of the group that was on the classic 300 plan so I upgraded the modem and decided to go ahead and upgrade to Gigablast. I have the following setup.

Modem: New SB8200 3.1

Router: Asus AC3100 

Wired Speedtest: 426Mbs Down/ 35Mbs up at all times of the day. 

I have taken a screenshot of what I see for channels but cannot upload it. 

Any recommendations?