My plan is 1.2Gbps internet speed but I am only getting 930 Mbps

I have an XB8, with a 6 cat cable, I should be getting faster speeds. But on the Xfinity site it states that if you connect with ethernet then you are capped at 940 mbps, so no matter what you pay for you get any higher. But it's the same on wifi. So basically, why can't I get higher speeds?

https://www.xfinity.com/support/articles/requirements-to-run-xfinity-internet-service