Comcast says my Motorola MG7315 Cable modem and WIFI router is "incompatible based on filters". What does that mean? Can I make the device compatible with their system by doing a firmware update or software setup modification? If not, any recommendations for a reasonably priced replacement? The equipment they recommend is fairly expensive.

Are you asking about this because you got a notification from Comcast for no reason, it just arrived as an email or paper mail message?

OR...

Did this come up because you are having problems with your equipment and a Comcast technician told you that your equipment was incompatible?

You can check to see if your equipment is compatible here:
https://www.xfinity.com/support/devices/#unauth

If this website says your equipment is compatible, then you should call Comcast tech support about the matter.

In general, firmware updates for modems are done by the carrier, not by the end user.

Thanks for your answer. I got a message from Comcast to upgrade with a list of "compatible" hardware.I was just wondering what "filters" they were talking about.