I have the Gigabit Conneciton Plan, but can't come close to 940/880Mbps

[#1]

Hello - I have the following:

• Verizon FIOS Gigabit Connection (up to 940/880Mbps)
• Verizon FIOS Quantum Gateway AC1750
• Desktop computer wired to the router (no WiFi for this particular connection)
• Cable run of under 50 feet of CAT6 cable from router to computer
• My desktop does have a 10/100/1000 Mbit Ethernet card.

When I run Google Speed test I typically get speeds of between 400-600Mbps download and 100Mbps upload.  

Is there anything I can do to get it closer to the stated limits of the plan?  

Thank you.

[#2]

https://www.verizon.com/SpeedTest/instantinternet.aspx

No test site other than the link above is accepted by Verizon Fios.

i have posted this many times that real world test speed sites are not on a proprietary network but have the bottlenecks and congestion and bad hops and rerouting as sites like speedtest net or google and others.

i get these numbers almost all the time. See my screen shot attached