I have an archer 6000 router and new netgear cm2000 nighthawk cable modem and a new 2.5 gb ethernet card in my pc. Max download speed i get on the speed test in the tplink app is around 600-750. Are there any other settings I can change to maximize the wired ethernet speed to my desktop? Is this router capable of faster speeds?

I am paying for a 1.2 gb connection and xfinity says my connection is good on their end. 

I have also installed/switched out cables to new cat 6 cables and restarted them