Internet does not work on Medion Akoya?

I have a problem. My laptop can't open internet pages. Google pages like Youtube, Gmail, etc. But there are the exception. Everything works as usual on my mobile phone. My laptop also indicates that I'm connected to the router. For me it has been like this for a long time:

A few days everything works and then a few days only Google works, etc.

Is this a known problem and how do I solve it?

In the worst case reinstall Windows