New Netgear CM2000 modem runs at 50% the speed of old Netgear CM1000 modem

Got a notice that my CM1000 modem was no longer supported so upgraded yesterday to CM2000.

CM1000's download speeds consistently averaged between 850 mbps and 950 mbps for cat 6 wired connections to router with cat 6 wire to mode. Last test was yesterday before the upgrade.

CM2000's download speeds consistently average between 400 mbps and 500 mbps on can 6 wired connects directly to modem.

Can't find any tech support phone numbers for Comcast or Xfinity and the bot is useless.