Slow internet & packet loss. Technicians have been out 3 times, buried new cable, and still cannot figure out why. HELP PLEASE!

Ever since we moved to our new address in Kent, WA we have had issues with our home internet speeds. We are supposed to be getting 1200 mbps, but often can't even break 100 mbps and it is absolutely NOT consistent. The speeds constantly are fluctuating and we often get packet loss when online gaming. We have had 3 technicians out from Xfinity and all could not figure out what the problem was. They had a new cable buried to our house, they scheduled specialists to update the equipment on our neighborhood's cable box which 2 different specialists came out and didn't seem to do much. One tech told me that the equipment in our neighborhood's cable box was outdated by 10+ years but he cannot swap them out. Then when the specialists came they did not do anything. I watched them open it up and fiddle around for 5-10 minutes and then leave. They never checked in with me or asked to test things out. They all just close out the workorders and don't communicate or test anything with us. NOTHING HAS CHANGED.

Just so you know our equipment, we have a new Netgear Nighthawk multi-gig modem bought in 2024 and my routers are the Google Mesh system (with 2 mesh points) which is capabble of gigabit internet. We have tried two different coax locations in our house and unfortunately our area does not offer fiber. We have given up and are desperate. 

I have spent months and months on the phone and chatting with Xfinity, and no other internet providers can even come close to the Xfinity speed in my area. I am out of options and we NEED HELP!!! Both my wife & I often work from home, plus we both game and stream along with our son. I have no idea what to do anymore...

PLEASE HELP!!!