@RouterArcher 

Every house/home is different so the router home size is just a general indication of what it can cover.

Many things affect coverage. Some things to do or consider.

• The 2.4 GHz band will get more distance but the 5 GHz band will be faster
• Location is important. Should be in a central location.
• The direction the router faces, the height, the direction of the antennas, moving it several feet can make a big difference.
• WIFI is obstructed by many things such as walls, fireplaces, metal in walls, electrical wires, floors, ...
• WIFI signals are affected by other WIFI and by many other types of devices such as cordless phones, microwaves, weather stations, wireless cameras, ...
• Give the router some space around it for both heat disbursements and signal improvement (for example, do not hide it in a bookcase or closet)
• Metal near the router such as an appliance can cause directional issues.
• Sometimes using specific WIFI channels and band widths helps.
• Some router have replaceable antennas which reported to help but not sure as I have not tried them.

I have a smaller house and because of the design, I use an extender to cover a problem area to get a strong reliable connection. However, I have many devices that are a farther distance away that do not have any issues connected to the router. Moving my router about six feet more to the center of the house made a big difference in my coverage. 

Although a router with the extender work for me when it becomes time to replace my router, I plan to consider a MESH system as it is designed to handle large and/or complicated designed areas.