Blazor项目使用相对URI遇连接被主动拒绝错误的排查与解决

我正在自学Blazor，遇到一个接口调用问题：使用相对URI api/employee 请求时，报错 {"No connection could be made because the target machine actively refused it."}，但改用完整URI https://localhost:44376/api/employee 就能正常请求。我希望能使用不带端口号的相对URI发起请求，以下是发起请求的GetAllEmployees方法代码：

public async Task<IEnumerable<Employee>> GetAllEmployees()
{
        bool isEmployeeListEmpty = true;;
        IEnumerable<Employee> employeeList = null; 

        try
        {
            //string uriEmployeeList = $"https://localhost:44376/api/employee";
            string uriEmployeeList = $"api/employee";
            var employees =  await JsonSerializer.DeserializeAsync<IEnumerable<Employee>>
                    (await _httpClient.GetStreamAsync(uriEmployeeList), new JsonSerializerOptions() { PropertyNameCaseInsensitive = true });
            if (employees != null)
            {
                isEmployeeListEmpty = false;
                employeeList = await JsonSerializer.DeserializeAsync<IEnumerable<Employee>>
                    (await _httpClient.GetStreamAsync(uriEmployeeList), new JsonSerializerOptions() { PropertyNameCaseInsensitive = true });
            }
            else 
            {
                isEmployeeListEmpty = true;
            }

            
        }
        catch (Exception ex)
        {
            Console.WriteLine("An exception occurred inside the GetAllEmployees() method of the EmployeeDataService class");
            Console.WriteLine(ex.Message);
        }

        if (!isEmployeeListEmpty)
            return employeeList;
        else
            return null;

}

开发环境为单机器上的IIS Express。

更新
问题已解决，根源在于：launchSettings.json 中配置的SSL端口为 44376，但Startup.cs里三个HttpClient对象的基地址设置成了https://localhost:44340/。将基地址的端口修改为44376，与launchSettings.json保持一致后，使用相对URI即可正常工作。

内容的提问来源于stack exchange，提问作者Ivan