Gaming Setup ?

Follow up to my post.

My online gaming experience continues to suffer from packet loss and lag. This has had me going nuts. I replaced my modem and still having the same issues. This brings me to the router. Looks like the router is my problem. For some reason when it is hooked up it shows 1000/Full bandwith on WAN and LAN ports. The speeds I see range from 40-90 down /10 up. After a recent internet speed upgrade from 150 down/10up to 500 down/10 up we've never seen those speeds. I did a full factory reset yesterday and installed latest firmware and am still getting the slow internet speed. My Xbox is hardlined using CAT6A cables into R7000P LAN PORT 1. I've tried other LAN PORTS with no improvement.   

Had a service tech stop by Friday and had them run tests and he claimed our new ARRIS SB8200 was faulty. I was able to return it and got a new one with the same results. The tech left a loaner Modem/Router combo and we had full speed 480 down/10.5 up no problems and the Xbox was seeing nothing less than 300 down/10.5 up. My Arris SB8200 conected to my R7000P hardlined to my Xbox never sees over 100 down/10up.  

This has me thinking the router is not able to push the speeds I'm paying for. I've seen others on here in other posts claiming poor performance too. I've seen others post about going to old firmware to get the performance back but this doesn't make sense. On paper this router is amazing but it does not live up to the speeds or performance as advertised. 

Thoughts or ideas on solution ?