I have wildcards in my API-Routes, like

[HttpGet("api/customers/{wildcard}/add")]

so that I can handle multiple instances of my application and manage the endpoints with a loadbalancer that knows where to redirect based on the wildcards value. I can then use the route

www.example.com/api/customers/contoso/add

No I want the same for the UI, but the following doesn't work:

var root = Directory.GetCurrentDirectory();
var fileServerOptions = new FileServerOptions()
{
    EnableDefaultFiles = true,
    EnableDirectoryBrowsing = false,
    RequestPath = new PathString("/customers/{wildcard}/app"),
    FileProvider = new PhysicalFileProvider(Path.Combine(root, "wwwroot"))
};
app.UseFileServer(fileServerOptions);

I cannot access the static file server via

www.example.com/customers/contoso/interface

it only works if I literally use

www.example.com/customers/{wildcard}/interface

Do you have any idea how I can accomplish the same behaviour that successfully works for the API-routes for the static file server aswell?