Why does new object in Linked List overwrite old object

Question

I am creating a two-sided linked list. For that I implemented a Node with the following attributes:

struct Node {
public:
    int Daten;

    Node* Next = nullptr;
    Node* Last = nullptr;

    Node() {
    }

    Node(int Daten) {
        this->Daten = Daten;
    }
};

I then implemented a class, which adds Nodes to my Linked list. I can add two Nodes to the list, and all the references work perfectly. As soon as I create an instance of the third Node, the programm assumes that I am trying to reference the second element in the linked list. This behaviour can be seen, because when I debug the code. The linked list works Perfectly with two elements, but as soon as I call the "Node" Class to create the third object of it, the second element gets overwritten by it. This is the code on my Linked List Class.

class LList {
public:
    Node head;
    Node* NodePtr = &head;

    void AddNode(int Key) {
        if (NodePtr != &head) {
            Node newnode(Key);
            NodePtr = &head;
            NodePtr->Next = &newnode;
            newnode.Last = NodePtr;
            NodePtr = NodePtr->Next;
        }
        else {
            head.Daten = Key;
            NodePtr = nullptr;
        }
    }


    void printList() {
        std::cout << "List status now: ";
        Node* Localcopy = &head;
        while (Localcopy != nullptr) {
            std::cout << Localcopy->Daten << ", ";
            Localcopy = Localcopy->Next;
        }
        std::cout << std::endl;
    }

};

This is my main function where the code gets executed.

int main() {
    LList mytree;
    mytree.AddNode(7); // Works perfectly up to here.
    mytree.printList();
    mytree.AddNode(4); // Works perfectly up to here.
    mytree.printList();
    mytree.AddNode(2); // The first element points to the third Element, and the Second gets lost  or overwritten.
    mytree.printList();

    return 0;
}

The output I get is the following:

List status now: 7,
List status now: 7, 4,
List status now: 7, 2,

That is all which is inside of my project. Why does this overwriting happen? Are there any mistakes that I am overlooking. How can I fix it?