Issue with internet losing connection frequently

Hello,

I use the Xfinity NOW internet plan with a Xfinity Wireless Gateway (like the Model numbers: DPC3939, DPC3941T, TC8717, and TG1682G). The gateway is connected directly to a Unifi Cloud Gateway Ultra for routing. I've had this setup since May 2024. A week ago, I've begun losing internet connection intermittently lasting from 5 seconds to 5 minutes before recovering OR requiring a restart of the Xfinity Wireless Gateway to restore connection so it could be out for hours unless the Xfinity Wireless Gateway is powercycled. I've had 3 consecutive notices in the last three days on my dashboard about routine maintenance in my area starting at 1 AM. I haven't seen any improvement day-to-day and am still getting intermittent complete disconnections from the internet that may or may not require restarting the modem.

The disconnections are occurring on the WAN side of my Unifi Cloud Gateway Ultra and are not device specific disconnections on the LAN. I have a suspicion the Xfinity Wireless Gateway is failing.

I've replaced the ethernet cable connecting the two gateways.

I've checked the coaxial cable to see if it's secured.

I've attempted to have xfinity assistant troubleshoot and pull logs multiple times (but it often fails).

What should my next step be to get back to having a reliable internet connection?