Archer AX21 v4.6

Tested speed several ways, I have a cox modem connected to the AX21. PC connected to the AX21 and also to a 1000 switch. I upgraded the modem and the output is 962 Mbps

but the speed on pc is 500 Mbps. I have cat 6 ethernet cables. When I set this up last year with an older 1Gig modem I was getting pretty close to 900. Now 500? Im paying for 1 Gig and not getting it. I have messed with it so much that I am about to give up. Spent a decent amount of money. 

I also tried to put modem in tunneling to the AX21. Now its back with the wifi on the modem turned off. My PC is latest hardware.

HELP