Your answer was very instructive and informative, thank you. I probably should have also noted that I had installed a new Netgear Nighthawk Model C7100v device in the past 2 weeks.
After reading your answer and a loooong talk with a Comcast tech rep, I learned that the 'boot file' (it may have another name) that Comcast uses when they were activating my new Netgear modem/router is a 'lesser' one than the boot file used when a Comcast supplied device is used. Thus, the user gets slower down and uplink speeds. It looks like a business strategy that 'encourages' you to either use a Comcast device or reduce the plan speeds
Since I had been getting 700-800 downlink and 30 uplink speeds before, I guess I'll return my Netgear and go back to my $14 a month Comcast device.
If you are subscribed to the gigabit speed tier, you will not be able to get gig speeds with that Netgear C7100v. It's only DOCSIS 3.0 capable. You'll need a DOCSIS 3.1 capable device. Otherwise it will default to using a lower speed boot / config file.
Quite welcome !