public class Sentry : MonoBehaviour
{
    private NavMeshAgent _navMeshAgent;
    private int _currentWaypointIndex = 0;

    public Transform[] waypoints;


    private void Start()
    {
        _navMeshAgent = GetComponent<NavMeshAgent>();
        _navMeshAgent.SetDestination(waypoints[_currentWaypointIndex].position);
    }

    private void Update()
    {
        if (_navMeshAgent.remainingDistance <= _navMeshAgent.stoppingDistance)
        {
            _currentWaypointIndex = (_currentWaypointIndex + 1) % waypoints.Length;
            _navMeshAgent.SetDestination(waypoints[_currentWaypointIndex].position);
        }
    }
}