Laptop does not recognize mobile phone (S9 +) for file transfer?

So first, it must be said that my USB cable is working properly.

You have to set the phone if you want to transfer only pictures or files. When I choose to transfer images everything works, but as soon as I go to file transfer, my phone is no longer displayed. What can this be?

I'm happy about answers

Did you indicate with your S9 that it should allow the data transmission? You can do that if you pull down from above and press on the window (for 3sec) which appears when you connect the phone mitm pc and then go to all data go.

Yes I have

You may have to install the driver on the laptop