The speeds that manufacturers advertise are generally silly, you'll never see those speeds in the real world.
Go to http://mydeviceinfo.xfinity.com and you can see your speed tier and your current modem. You can also see approved devices for your speed tier.
Be aware that you either need a modem AND router or a combo device known as a gateway.
I took the speed test from the link that you sent. This is what it gave to me. download speed 53.0 mbps & upload speed 12.3 mbps. That seems really slow compared to what I have seen. I now have an Arris modem but I don't know the model.
How would I get a faster speed with Comcast? Thank you for your help.
my speed seems to be very low. download is 53 and upload is 12. How would I get a faster speed?
Thank you for your help.
Which type of connection are you using - wifi or Internet? Wifi will always be slower than ethernet.