WiFi is simply radio. There are a lot of factors that can change the performance of a radio signal. Are you in a steel building or a building with vertical steel beams? That can change the signal "bounce". If everything is OK with the router it has to be something in the environment or the receiver. Try it in a different room. You said you were 2 to 3 meters away. Have you moved to a different room? Is the router in a closet? Etc
If it works line of sight in one room but not another there is something in that room that presents a problem to the radio signal.
Are you sitting between the router and the computer? That sometimes presents problems. Some people absorb radio signals more than others.
A cheap directional booster can be made...