Asp.net core 2.2 multiple get requests

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ASP.NET

I used this tutorial to start with core 2.2 Tutorial: Create a web API with ASP.NET Core MVC | Microsoft Docs[^], filed off the serial numbers and changed the colour but the same style.

All went well until I wanted to get a filtered selection so I need a second (and third) GET. Using Postman I get a duplicate GET error with
https://localhost:44334/api/userdetails?FleetID=1

There is no routing in the Startup.cs

What I have tried:

Controller starts with

[Route("api/[controller]")]
[ApiController]
public class UserDetailsController : ControllerBase
    {
		DAL.UserDetails dsUserDetails = new UserDetails();

		[HttpGet]
		public ActionResult<IEnumerable<UserDetailsDB>> GetUsers()
		{
			IEnumerable<UserDetailsDB> lResult = dsUserDetails.UserDetailsList();
			return lResult.ToList();
		}

Second GET with additional filter - what is the decoration for this or the calling syntax for the GET

[HttpGet]
public ActionResult<IEnumerable<UserDetailsDB>> GetUserForFleet([FromQuery] int FleetID)
{
  IEnumerable<UserDetailsDB> lResult = dsUserDetails.UserDetailsForFleet(FleetID);
  return lResult.ToList();
}