IM ONLY GETTING 300Mbps WHEN I AM PAYING FOR THE 1200Mbps [Edited]

I never seen 1200mbps on my MacBook Air M2, MacBook Pro M1, iPhone 14 Pro, 13 Pro, 13, XR or SE 2nd Gen never seen more than 300 mbps and on my son ps5 ethernet wired the highest was 600mbps. 

Doesn't make sense to pay for this might have to go back to 400mbps.

I'm also using a xfinity XB8