C7000V2 not meeting Comcast provided speeds

I recently upgrade my Comcast internet speeds from 400 to 800. Ran a speed test and noticed I was only get 300. Comcast came out and checked all the lines with no issues, said 1300 was coming thru the cable to the modem. Said it’s an issue with the modem router and try a factory reset. Tried a factory reset and still no getting the 800 speeds and only getting 300. Firmware is up to date with the latest V1.03.03