speed not match my plan

What is the exact make and model number of the "modem" ? Is there a separate router / WiFi in the mix here ? If so, what is the exact make and model number of it ? Are you testing with a WiFi connection or via a hardwired / ethernet connection ? If it's ethernet, does the device that you are testing with have at least a 10/100/1000 (gigabit) port ? Tried swapping out the ethernet cable for another ?

Ok so as I asked, what is the exact make and model number of it ? And please answer the rest of my questions....

Ok. For clarity, I'll ask again. Does the laptop have a gigabit-capable ethernet port / NIC adapter ? And for a test, instead of using the router's built-in utility speed test, what speeds do you get when testing here;

https://speedtest.xfinity.com/ 

O/k, perhaps they are not pushing the correct speed configuration file for the speed tier that you are subscribed to to the modem ? 

I'm going to escalate your issue to the Comcast corporate employees (The Digital Care Team) who are available to these boards. They will be able to poll the modem and confirm that the provisioning and account data in their backend database is correct and complete, and that the correct configuration / bootfile for your subscribed to speed tier is being pushed to the modem.. You should get a reply here in your topic. Good luck !

It was a pleasure speaking with you @user_d22s1e5! Happy we could help resolve your slower-than-expected speed by swapping out the ethernet cable with a new one. Thank you again for choosing Xfinity, and please let us know if anything more were to come up. Take care! 

@XfinityThomasA 

Thank you for sharing what the solution was here with the community at large !