Ongoing internet outages and major issues

Hi, I've had an extremely unreliable internet connection for months (even prior to the pandemic). There's no pattern to its issues and it's unusable for anything that requires a stable connection such as voice conferencing. The latency for all connections spikes to 200ms+ and there are packets being dropped, connections lost, then it'll go back to normal.

Old router/model combo: Netgear C7000
New router/model combo: Netgear C7000v2

I've tried the following things listed below to save time (https://forums.xfinity.com/t5/Internet/ANSWERED-Tips-for-troubleshooting-your-Xfinity-Internet/ta-p/2941127😞

1. No service outages reported in our area on the Xfinity website
2. Verified my devices meet minimum requirements and my router/modem combo are compatible.
3. We bought an entirely new modem/router combo, tried connecting multiple systems through that, exact same issues.
4. We tried switching the coaxial cables
5. We tried using a different coaxial outlet in the house
6. We tried resetting every device multiple times whenever appropriate
7. The lights on the router/modem indicate no issues
8. Signal levels appear to be OK
9. We have contacted online support twice and they were unable to fix it + said it looked fine from their end
10. We had a tech visit, redo the wiring to our house from the pole outside, but they were unable to fix it. He suggested a modem issue, but we subsequently bought the new one and tested it too--as you can see, that wasn't it.
11. I don't see any uncorrected errors in the modem signal log
12. I don't see any timeouts or other pertinent lines in the event log

Here are screenshots of pings / traceroutes showing the connection issues, and also my modem's signal levels: https://imgur.com/a/FYDEgDt

So I'm not sure what to do at this point. We absolutely need this internet service to work from home during the pandemic, but we aren't getting a usable service. Is there any way to escalate this or get someone to take a closer look?

 

Thanks!