i'm not getting the speed i'm paying for

I recenly just upgraded from 50 to 100 to 300. Knowing i needed a faster wifi router, i upgraded to a newer netgear ac1000 router (model R6080). Sadly, i'm still seeing a max speed of about 70-80Mb/s, although my upload speeds are at the advertised 30Mb/s. the modem i have is docsys 3.0

any ideas?

Thanks