Try this

Buy an ethernet cable and hook that up and see if your speed is better it should be and then you enable the ethernet networking your computer. I get 500 Mbp from Xfinity in my download speed is only 100 mbp and the reason is my computer is 10 years old it's a laptop and it just doesn't have the capability of running any faster than that so I can live with that routers are very particular and funny when you're setting him up if you don't get everything just right they don't work right