@Jg711 wrote: Have been told by multiple techs that Comcast does not push firmware updates ...
That's mostly incorrect. Although Comcast's first-line reps cannot push firmware updates, their systems push them automatically when they detect that an update is available and the modem is power cycled or reset. Higher level techs can push firmware, but this is rarely needed.
What firmware version do you have, what version do you think you need, and why do you think you need it?
"Ongoing connectivity issues" are most likely due to a poor connection between the modem and Comcast's network, usually in or near your home. See Connection Troubleshooting Tips. If you still need help, please provide Information Requested for Connection-Related Posts.
If you are using Wifi it's best to switch to an Ethernet cable connection if possible while measuring speed and checking the reliability of your connection to Comcast.
If you can't find the problem or you'd rather have Comcast do the troubleshooting, call them at the phone number on your bill or 1-800-Comcast, or chat with them using the Internet Support option at https://support.xfinity.com/chat. If they can't fix the problem remotely, insist they send a tech out to identify the cause and correct it.
If the tech finds bad coax, splitters, amplifiers, or connections in your home (even if Comcast originally supplied them) you'll probably have to pay for the visit unless you have or sign up for their Service Protection Plan (https://www.xfinity.com/support/articles/service-protection-plan, about $6/mo) and keep it for at least 60 days. If the trouble is due to a faulty Comcast modem, eMTA, gateway device, or anything outside your home, you shouldn't be charged.