Router issue

Wi-Fi is radio waves, meaning your router broadcasts in all directions from a central location. If your router is in a far corner of your house, then you’re covering a great deal of the outside world unnecessarily. If you can, move your router to a more centralized location. The closer you can put your router to the center of your coverage area, the better reception will be throughout your house.

If you have external antennas, you can try adjusting those too. Alternating between fully vertical and fully horizontal positions can help reach in multiple direction