Need 160MHZ Bandwith Available to me

This is driving me absolutely crazy. I used to be able to modify my channel and width settings, but for some reason Xfinity decided to "Auto-Tune" the settings and not allow us to change them anymore and its driving me up the wall because i have an EDup 3200Mbit PCI-X controller that used to connect at 1.7Gbit and get 1085/41 speedtests and now I can get the thing to go over a 400mbit speedtestr because the "auto-Tune set my channel bandwith to 80mhz auto instead of 160mhz auto. PLEASE HELP WITH THIS. I work from home and transfer large files back and forth from work and need my full gigabit speed. my laptop direct connected get 1000 speed test all day, but my main work machine is not possible to have a cable run to it.

I have a Xfinity Arris TG442 AX6 router.