Why one room never gets Wi-Fi
A router inside a cabinet, on the floor, or at the far end of a garage loses most of its signal before it reaches the bedrooms. Put it in the open, near the middle of the home, and retest. If a room is still weak, a mesh node in the hallway between the router and that room works better than a node inside the dead room. Extenders that create a second network name cause phones to cling to the weak signal. Ask for one network name when the system supports it.