Is it possible to contact a support person any more?

Start here;

https://forums.xfinity.com/t5/Your-Home-Network/Internet-Troubleshooting-Tips/m-p/3310447#M316652

Thank you very much for your response. I have been through most of that but it is helpful to have the range of power and SNR which I hadn't previously found. I've detected a pattern over the last 3 to 4 weeks that it goes down every single day around 10AM eastern time (it also frequently goes down during peak neighborhood usage time like early evening and almost never late at night). When it goes down at 10am like clockwork, the event log entries show broadcast maintenance request then unicast maintenance request begin then no unicast maintenance response t3 timeout then iterated through similar errors until it starts logging ranging request timeouts / retires exhausted then it knocks offline and is unable to reconnect after rebooting the modem. Then anywhere from 15 to 90 minutes later it will reconnect and work until it crashes again.

After this morning's crash, I was able to get back online about 10 minutes later, and after 8 minutes back online, it had logged (64) T3 errors and (1) T4 error. Watching the upstream signal, it will read 51dB on all 4 channels and then on some refreshes show 30 on one channel and the downstream is doing similar but with different numbers obviously. Not sure what the uncorrectable codeword are, but those numbers exceeded 10,000 after 8 minutes back online.

Every time I call the support number and say I want help with a technical issue and that I want to talk to a person, it forwards me to an IVR system that says my service is fine, my modem is detected, thanks for calling, then hangs up on me. When I called to try to downgrade my service it said they weren't open and told me to call back during business hours (which it was at the time) or visit a store and hung up on me.

After working for a little over 20 minutes it has gone down again, and that thing in the event log before knocking offline is

Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out

Thank you. I have been watching signal levels and errors over the last few days. The cable I was using is an RG6 provided by comcast. I have seen downstream signal strength deviate between -0.2 and -6 at different times of day. I replaced the cable with a lower end one just to see if it made a difference and it has decreased the downstream SNR and I dont see much other difference.

I have noticed that since the construction down the road, a service "upgrade" also roughly coincided with this, and I think the construction where my errors began was an attempt to increase bandwidth to the neighborhood. Since the road work, my upstream had never once obtained a bonded connection, and I think most of the T3 times out are channels 2 through 4 on the upstream attempting to range/connect but they fail 100% of the time. I found a page in my account info under troubleshooting that says I have 4 up and 4 down docsis signals, however it will not allow more than one upstream channel to connect at any time. According to the doc linked above, the modem will increase upstream power and retry until exhausted, so might that explain my 51dB upstream signal?

To add more fun to the fire, Comcast is now listing my modem as not compatible, however it is the same model they provided me when I was renting and I purchased it based on their recommendation, so apparently I need to buy a new modem but they never bothered to tell me? This is all so ridiculous, but I do appreciate the input because Comcast seems to be going out of their way to NOT help whatsoever. The modem us a UBEE DDM3513