How to send a packet beyond NAT?

Question

Java

There is a local network. It has multiple routers.
It is necessary to send a packet to all clients..
When using a similar code in JAVA

public class SendAll {
    static DatagramSocket s;
    static DatagramPacket dp;
    public SendAll(String Line){
        
        try{s=new DatagramSocket();
        }catch(Exception ex){}
        
        try{sendString(Line);
        }catch(Exception ex){}
        
        s.close();
    }
    static void sendString(String str)throws IOException{
        byte[]buf=str.getBytes();
        dp=new DatagramPacket(buf,buf.length,InetAddress.getByName(main.Const.BROADCAST),main.Const.PORT);
        s.send(dp);
    }
}

The packet is sent only to clients of the same subnet, for example, clients with IP 192.168.1.1-254,
but will not be sent to clients 192.168.2.1-254, NAT is used..
how to send the packet further?

Answer 1

If I understand the code correctly, then you are trying to send a UDP broadcast. If so, then no way. Routers usually never broadcast beyond their own network so that there are no network storms.