Hello Dawn Schulz,
Thanks for visiting us on the forums with your question, I highly recommend the TP-Link Deco Tri-Band Mesh WiFi 6 router. This will cover up to 5500 Sq. Ft.
Alternatively, I recommend the eero Pro 6 Tri-Band Mesh system which comes with 1 more mesh device than the TP-link.
The nice thing about these Mesh systems is you can hardwire a device that does not support Wi-Fi 6 to achieve higher throughput.
Lastly, I recommend replacing your cable modem once every 2 years.
Recommended Arris cable modem if you are not using any Panoramic connected receivers for your TV’s