[EdFNJ]

Comcast has a data cap. It's quite a lot of data (1.2 TERAbytes per month IIRC) but if you need unlimited data, or download lots of large files like 4K movies or equiv of BluRays's , or watch loads of streaming 4K or have a streaming TV service instead of cable the only way to go is with their modem and their unlimited data package. Why might you need unlimited (or more than the data cap) ? Maybe if you have security cameras that stream with a decent resolution and/or stream to cloud 24/7 rather than only when someone is close by. If you have none of that buy your own modem/router just make sure you know what you are getting. Their mode WITH unlimited data is $25/month, data overage on your modem is $10 gig, unlimited data with YOUR modem is $30 month. Do the math.