Why does the router crash at higher load?

I have the problem for 2 weeks that my router crashes when loading movies on the Internet or ordinary downloads.

I had already tried the following things:

Reset the router completely to factory settings or reset the devices that are connected to the router.

As soon as the problem arises, the devices are connected to the Internet, but they no longer have access to it. If I disconnect the device that was responsible for the crash, the internet is right back and can be used.

If I Something on my laptop, the router crashes; I disconnect the laptop directly from the Internet, that's how it works again.

Now to the data:

The router is Fritzbox and a 50k line is present.

And if you download something with another device?

Is your FritzBox very old?

Do you use the current firmware?

Yes the current firmware is installed: /

In fact, I found that only the laptop crashes the router.

Then it is not on the router.

Maybe she is just broken if she is already very old.

Yes, but the problem is that my (Surface Pro 6) with other routers does not cause a crash. : /

Then the problem mglw lies in the settings for connecting to the routers.