getting network error

I m getting network error

unable to understand what is the error

public class UserModel
{
public int UserId { get; set; }
public String FullName { get; set; }
public String UserEmail { get; set; }
public String Password { get; set; }
static string ConnectionString = "Data Source=DESKTOP-O00000/SQL2017;Initial Catalog=nsroute;Integrated Security=True";
public static IEnumerable GetUserDetails()
{
List userdetailslist = new List();
using (IDbConnection con = new SqlConnection(ConnectionString))
{
if (con.State == ConnectionState.Closed)
con.Open();
userdetailslist = con.Query("GetUserDetails").ToList();
}
return userdetailslist;
}
}