CM1150V Dropping packets

My CM1150V worked when I first bought it in October and then in late November it started dropping packets. Netgear said it was an Xfinity problem but after having Xfinity come out and check the lines and doing multiple troubleshooting, the problem could not be resolved.

I connected a different 1Gbps Modem from Motorola and it has been working fine. What are options for getting the CM1150V to work again? Are there firmware updates?