CAX30s is not giving speed upto 1000mbps

[gulmoharc]

Hello, I have upgraded Xfinity speed to 1000mbps, but Nighthawk CAX30S gives only 400-500mbps. I called Xfinity tech, and he checked everything; as per him, all signals are good, and the modem should give full speed up to 1000mbps. I tried to restart, then reset and start from scratch but still no luck. Can someone please help me out?
Thanks in advance.

[plemans]

How are you testing speeds? 

Wired? With a wireless device? 

What device? What site? 

You said you did factory reset the cax and reinstall it? 

do you have a screensnip of the cable connections page and event logs? (xfinity's first response is always that its fine)