wifi internet weird problem

The Wi-Fi radio is configured for the wrong country.

Each country regulates wireless networking differently. Wi-Fi devices are restricted to certain frequencies and power levels. The client devices try to find out where they are and configure themselves accordingly. Since a wireless access point (WAP) usually does not move across national boundaries, the Wi-Fi regulatory domain (country code) is set by querying the first one to respond when the client initializes itself. You don't have any direct control over it on the client. If your device is picking up the wrong country code, and is therefore locked out of using some Wi-Fi channels or operating at full power, the only lasting solution is to fix or remove the misconfigured WAP.

First check the setting of your own WAP. Change the country code, if applicable. I can't be more specific, because all routers are different. After changing the code, turn Wi-Fi off and back on.

If your WAP doesn't broadcast a country code, you should replace it with one that does.

To find out which other nearby WAP's are broadcasting a wrong country code, hold down the option key and pull down the Wi-Fi menu in the menu bar. Hover the cursor over each of the menu items representing a WAP. A tooltip (small box) will appear after a moment, showing, among other things, the country code being broadcast by that WAP.

Compare the code with the one your Wi-Fi interface has adopted. If a WAP with a wrong code is not under your control, try restarting the computer as close as possible to your own router.

this is a configuration set by the router and nothing to do with my laptop

As I wrote, it's set by a router—not necessarily yours, though it could be.