Look at the back of your desktop. Many have one or two small antennas screwed into the back panel. Some have none, because the Wi-Fi is a USB stick.

If there are antennas on the back.

They are often short and point at the wall. Make three changes.

Turn the computer so the antennas are not pressed against the wall or a metal shelf.

Stand the antennas straight up, away from the case and cables.

Replace short antennas with a longer one. Many antennas screw on and off at the connector. A replacement with a longer reach, or one on a cable with a magnetic base, lets you place the antenna on top of the desk or on the case. Check the connector type before you order, and match it.

Pick a spot high and in the open. Height helps. Metal beside the antenna does not.

If it is a USB Wi-Fi stick.

A stick plugged into the back of the case is behind metal. Use a USB extension cable and put the stick on the desk in the open.

A small USB adapter is weaker than a good internal card with real antennas. Sometimes the answer is a better adapter, not a longer cable.

If the computer has no Wi-Fi at all.

You can add a USB adapter, or an internal card with antennas. Cards go inside the case, so that is a job for me if you are not comfortable opening it.

Then measure again.

Run the tests from Part 2. Did the signal percentage go up? Did the speed at the desk get closer to the speed by the router?

If yes, you are done.

If the signal is still weak after the antenna is in the open, the distance or the walls are the problem. Part 4 is the answer.

Tomorrow: Part 4, When a Cable Is the Better Answer.