Not getting the speed I'm paying for.

I have the High Speed Ultimate package that gives 300Mbps/Down and 30Mbps/Up. I'm getting the advertised upload speed of 30Mbps but i'm not even getting 1/3 of the download speed. I'm only getting 80Mbs on average with 90Mbs at the highest.

I have an Arris Surfboard SB8200 DOCSIS 3.1 Modem with an Asus AC5300 Router.

I'm testing speeds through a wired connection. Going directly from the router to my PC. Wireless is even slower but that's to be expected of a wireless connection. The issue is that I'm not even getting a third of the speed i'm paying for over a wired connection.