Wrong modem listed on account, speeds same as old plan

I recently upgraded to 1000 Mbps internet service from 300 Mbps and purchased a Netgear CM700 modem (listed as supporting wired download speed up to 935 Mbps). I successfully activated the modem using the Xfinity app, but my download speeds are still around 300 Mbps and my old modem is still shown on My Device Info on the Xfinity website. I have tried restarting the modem and activating it again but the app just prompts me to chat with a support agent.