Download speed limited to 300 Mbps on 1000 Mbps plan

Service was started last week, the speeds have never gone over 300Mbps, but the plan we pay for is 1000Mbps. I am using a Comcast provided modem/router and am hardwired with Cat6. I have confirmed the computer and all cables can do gigabit speeds.

I had an appointment scheduled for a technician to come out but was called by "Advanced Technical Support" before the appointment. The person that called was not able to fix the issue but still canceled the appointment I had scheduled.

I am running out of things to try, next step will be to cancel the service. I understand that speeds may be lowered during certain times but it has never gone over 300Mbps which is ~25% of the speed we are paying extra for. I believe a setting is incorrect on Xfinity's side, possibly the provisioning is incorrect.