CM600 Packet Loss and Problem with power & SNR on downstream channels (Spectrum)

Hi All,

For the last couple of months, I've had a recurring issue with my internet connection.  After working fine for a few hours or days, internet speed will slow to a crawl (supposed to be up to 200 Mbps and it's running at 1-10 Mbps) with signficant packet loss (20-40%).  I reboot my modem and this issue will go away for some period of time before returning.  I've talked with Spectrum tech support and had a tech comeout to check everything.  Obviously, Spectrum is blaming my hardware, and the tech showed me that he could get up to gigabit speed on the incoming cable line.

When I plug directly into my modem when this issue is occuring, it looks like the problem may be on the downstream channels.  Once the modem starts locking past channel 16, the packet loss starts.  I'm attaching a screenshots from modem webpage when this is occurring.  I'd hate to replace my modem and then find out that this issue is on Spectrum's end after all.  Is there anything else I should try before replacing the modem?  Thanks!