Same problem in 80906 also started after hardware upgrade that required downtime in my area, and using speedtest app it seems performance is worse after the upgrade service is extreme pro internet up to 500 Mbps, modem is cgm4140com.
I have been having the exact same issue (and then some) for the same period of time. I had reliable speed and connectivity since upgrading to Gigabit last December 2019, but ever since "network enhancements" were made in my neighborhood in September 2020, the app has not recognized either my modem/gateway, or my main cable box, even though the services all still work.
Well, most of the time.
I have also been disconnected from the internet at least once every 2-3 days, at various times throughout the day, where my modem/gateway requires a hard reset.
I haven't called, because I haven't had the time to go through the hurdles of hoping to find someone who can resolve this issue, but I would be ecstatic to get this resolved.