Arris 8200 modem flips between DOCSIS 3.0 and 3.1 (blue light to green)

Howdy, I have an ARRIS 8200 modem and and 1.2 Gbps Xfinity plan.  The downstream light on my Arris 8200 modem changes from blue (DOCSIS 3.1) to Green (DOCSIS 3.0) several times per hour.

I'd been having disconnections from the internet every few days recently and Xfinity sent a tech out today.  They checked everything inside and outside of the house. They did quite a bit of improvement with cable terminations both in and out of the house and even replaced what was apparently the wrong power supply for the Xfinity amplifier in the home's wiring closet. When the tech left he said everything was great now.

It's too early to know if the disconnection issue is resolved - I hope it is, but the issue with the indicator light on the modem flipping back and forth hasn't been resolved and my last speed test using the Xfinity speed test site was sub-500 Mbps on a wired computer.  Not great.

What should I be looking at, signal level wise to figure out if this is a Xfinity issue or a bad modem?

Thank you