Mouse and keyboard with USB extension do not work on the computer?

I recently purchased 2 USB extension cables (7.5m) for my mouse and keyboard (https://www.amazon.de/gp/product/B077Z5CS2H/

Now my desktop PC constantly shows me "USB device could not be detected." and in device manager, devices are only recognized as "Unknown Devises," while connecting to a laptop works fine. What could that be? Do I have to get other cables for my computer (so-called active cable)?

But you have not hanged the USB cable to 15m total length together?

Yes an active cable would have been the right choice, according to the specification you should have a repeater every 5 meters.

In your case, wireless mouse + keyboard would be more useful.

Everything about 5m is critical on USB: can go, but does not have to. You would ever need an active hub in the middle of the cables.

I only connected one cable at a time with mouse and keyboard. But why does not the connection on the laptop and the computer work? Is it maybe a driver problem?

So is it just luck that the connection to the laptop works and not on the computer?

Exactly.

It probably works just like that on the laptop. This has nothing to do with drivers, but with how well the built-in USB controllers are.

As spelman already said, the solution is critical. At repeaters you can't pass, so I advise you to build everything wirelessly.

OK thanks!

Alright thanks!

Wired mouse and keyboard are passive elements without their own "power supply". They are powered only by USB.

USB has always 5V - USB2 has according to specification 500mA - USB3 900mA

A cable that has been extended so much will have too much power to feed the devices properly. A connection to USB3 would be preferable - maybe it works so synonymous s.Laptop?

Repeaters are again complex and expensive - because then rather take a wireless solution.