Ping issues for the last 4 months

so recently over the past 4 months i've been having issues with my ping, every 5 seconds or so my ping spikes by 200ms sometimes even worse, i have a xb8 modem on the gigabyte plan, the weird part is using the internet is fine and surfing the web and watching videos you wouldnt even notice a issue, but when you try to stream or play games it's a different story, constant packet loss ranging from 10 to 30 % i've even went through steps of troubleshooting myself i pinged my modems connection with my pc to check for packet loss and it showed 0% now the interesting part when i pinged the xfinity domain server it shows 14 to 23% packet loss, i need someone whos advanced enough to resolve this issue, i've had 4 technicians come to my residence from a regular one to a advanced technician all the way up to a senior technician and the issue still persists, i've had my modem changed 4 times in the last 3 months and the issue still hasnt been resolved. i have also made sure to test over either net and wifi the issue happens on both connection types. and on different devices.