Why doesn't VS 2017 see the unity monobehaviour class?

Question

Unity

After installing the latest unity 2018.3.0f2, no .sln file is created when creating a project. And Visual Studio does not see the Yunet class, the hints do not work. in the settings, the checkbox is not active:

Answer 1

When you try to create a project (Open c# project) is there something in the logs of the unit?
Perhaps a banal reinstallation is needed - it looks like VSTU has not become normal.