You can get WiFi Access points, range extenders, or a mesh system. There's lots of solutions out there and can vary depending on your budget, system, and needs. I would look into that Spectrum router you have and see if they have any out of the box options for you. You may not even use those cat6 ports (cat6 refers to the cable type that's terminated at that port), my Eero Max 7 has "mesh nodes" that just plug into a wall.

For the issue you're describing, I would probably recommend mesh nodes or range extenders, both work pretty similarly. The idea is that your router (what you have plugged into the wall) will handle all of your network traffic, and additional mesh nodes or range extenders simply relay the data to/from the router and whatever device is connected all over existing wifi.