An easy way to solve this, without the hassle of running long cords around your home, is a Wi-Fi range extender, which will pick up your router's Wi-Fi signal, amplify it, and rebroadcast it.
If you have a really fast internet connection in the Gigabit range, then you’ll want a high-end mesh router system like ... Even better, as long as you’re subscribed to the service Incogni ...