If your wireless card came already installed when you bought your laptop, we highly recommend that you contact your computer manufacturer to see if they have any update for their drivers that might resolve the issue. Also checking router configuration might help. If you installed the wireless card after you bought the computer and if it is Intel's, you can check the link below that might improve your connectivity.
*Important to know: Integration, which is replacing the original wireless card that came installed in the computer when you bought it for another one, is not supported by Intel as this procedure is subject to regulatory approval and the adapter may not support local regulations. Only your system manufacturer is entitled to provide the list of validated and certified adapters that are compatible with your system so for more information you may contact them directly.
Furthermore, Intel(R) Wireless cards for laptops are meant to be professionally installed by the Original Equipment Manufacturer commonly known as OEM Technicians on certified systems only.
Please, take a look at the links below for further information on this matter. Intel® Wi-Fi Products — Regulatory Information Regarding Hardware Installation or Upgrade and Intel® Wi-Fi Products — Why Doesn't My Laptop Recognize My New Intel Wireless Adapter?
Hi, aleki_intel, thank you for your answer.
The problem is not limited to my laptop. I don't have internet access in other devices aswell when this problem occurs, so the issue is not related to the wireless card. It certainly has something to do with the router configuration, but I haven't found a solution yet and everything there looks fine to my inexpert eyes.
In this particular case, Your best option would be to contact the manufacturer of your router for further assistance as they are the only ones that can help you at this point. Here are the links to support to your router: Download for TL-WR541G V7 - Welcome to TP-LINK and Contact Technical Support - Welcome to TP-LINK - You may also want to use their Forum support by clicking on this link: TP-LINK Forums - We do hope you may have you issue resolved as soon as possible.