CBR750 now not working with Xfinity

I'm also in the Denver area, and having similar problems with my Orbi CBR750. I bought the Orbi in May 2021 when I upgraded to 1.2Gbps service. It worked perfectly for about 16 months, showing download speeds up to 1.4Gbps. In October, I was notified by ComCast that they were doing an "upgrade" in my service area, with intermittent outages over the course of a week. Following this "upgrade" the Orbi would work fine for about 48 hours, then the download speed would slow to almost nothing. If I rebooted it, it would continue working, but I was getting tired of the frequent outages and having to reboot every couple of days.

Last weekend it happened on Saturday morning, so I decided to call Xfinity for support. The agent asked all kinds of inane questions about how many devices I had connected, etc. without really understanding the issue. Then she told me that my equipment was "outdated" and needed to up replaced, as the CBR750 is no longer on their approved device list.

I am very frustrated by this, as the published specs saying DOCSIS 3.1 and 32x8 channel bonding would appear that it should be compatible. I don't know whether to be more upset with NetGear or ComCast? It seems to me that ComCast has changed something that makes these devices incompatible, but they don't seem to be able to articulate it.

The only thing that I have found from searching online is that the CBR750 may use an Intel Puma chipset, which are known to have issues?

In any event, after only 18 months after buying a state-of-the-art DOCSIS3.1 cable modem with WiFi6 mesh networking, I'm basically left holding $500 worth of junk, and I've had to spend another $500 to replace it. This time NOT going with NetGear, even though it might really be ComCast's fault.

I'd really like for them to explain why any DOCSIS3.1 modem isn't compatible?