Netgear CM400

Xfinity has informed me my modem is "end of life." What exactly does that mean? It appears to work fine except when they have a service problem. Modem is bottom of the line with mbps of up to 100, but my bottom of the line Comcast service plan has maximum download of 50 mbps and upload of 10 mbps: I operate at speeds much lower, by factors of 10 lower... Netgear CM400 is still sold as compatible with Infinity; a Netgear consumer rep says my modem is perfectly good if it works, and it does EXCEPT in the last two weeks. My Internet has been dropped several times. Each time I make an appointment for service, then the Internet comes back on and I cancel the appointment. The automated Infinity service at first said there was a problem in my area, but now a person has told me my modem is at "end of life," AND that there have been several service outages in my area. So what do they mean?