How do I run thread-safe random numbers in async actions on ASP.Net?

How do I run thread-safe random numbers in async actions?

It always return zero. I tried to to make a instance in startup.cs which set a static istance of the current but it still always return zero.

I am using ASP.Net Core.

public class SafeRandom
{
    public static SafeRandom Instance { get; private set; }

    public SafeRandom()
    {
        Instance = this;
    }

    private readonly static Random _global = new Random();
    [ThreadStatic]
    private Random _local;

    public int Next(int min,int max)
    {
        Random inst = _local;
        if (inst == null)
        {
            int seed;
            lock (_global) seed = _global.Next();
            _local = inst = new Random(seed);
        }
        return inst.Next(min,max);
    }
}