have Xfinity giggit extra plan but speed test shows only 200 mbps...Why??

I am an Xfinity user and noticed my upload/download speeds are NOWhere near the 1 gigabit speeds that are mentioned on my bill.

i am renting a cable modem from Xfinity as well (i do have voice option but probably won't be needing it much more).   i know the cable modem is white but can't make out brand name, etc.

per a speed test on the internet i am getting 200 mbps, not 1 gig.   So why am i not even getting 1/5 of the speed...i can see it being close to 1 Gig but 200 is not even close!!

So what is going on and how can i get the speeds as mentioned on the plan that i have??