Internet only on the laptop EXTREMELY slow?

I'm completely desperate, since a few days the internet on my laptop is completely exhausted. On all other devices everything is fine and I have everywhere (even on said laptop) all the bars.

The best and most annoying example is that if I want to Google something (no matter which browser) it is only 2-3 minutes white and then it says that the page could not be reached.

Have already tried a lot of what was recommended in forums and so, cache empty this, has brought nothing. From the complicated stuff I understand only station so it would be nice to explain something simple if someone has a possible solution.