A desktop does not move. That is a reason to use a cable.

A cable is faster than Wi-Fi. It does not drop. It does not care about walls.

Option 1. Ethernet cable from the router.

This is the best answer. Plug one end into the router, the other into the computer. Almost every desktop has an Ethernet port.

The problem is the distance. A cable that runs across a room is a trip hazard. A cable through walls is a project.

Flat cables fit under rugs and along baseboards. Cables come in long lengths. If the router is near, this takes five minutes.

Option 2. Powerline adapters.

You plug one adapter into an outlet near the router and connect it to the router with a short cable. You plug the second adapter into an outlet near the computer and connect it to the computer.

The signal travels through the building's electrical wiring.

It works well in some buildings and poorly in others. Older wiring and surge strips can cut the speed a lot. Plug them straight into the wall, not into a power strip. If it does not work, return it.

Option 3. A second access point, wired.

If you can run a cable to a second location, a wired access point there gives the computer a strong signal close by. Then you have a stronger Wi-Fi and a cable together. This is how businesses do it.

What I would not buy first.

A cheap Wi-Fi extender for a desktop. Part 5 covers why.

How to choose.

Close enough to run a cable: Option 1.

Cannot run a cable, building wiring is decent: Option 2.

Want better coverage for the whole space: Option 3, or Part 5.

Tomorrow: Part 5, The Router End.