Non lista tutti gli IP della LAN

[nuklear]

La mia LAN è composta da:
stampante: 192.168.1.100
pc-mac: 192.168.1.101
pc-win: 192.168.1.102
router: 192.168.1.254

Questa procedura che mi dovrebbe listare tutti gli ip sopra indicati in una jlist:

public void listIP(){
        try 
              {
             
            InetAddress address;  
            DefaultListModel iplan = new DefaultListModel();
            jList1.setModel(iplan);
            InetAddress localhost = InetAddress.getLocalHost();
            iplan.addElement(localhost.getHostAddress());
            String ip;
            ip = localhost.getHostAddress();
            
            for (int i = 0; i < 256; i++)
            {
                try
                {
                String currIP;
                currIP = ip.substring(0,ip.length()-3)+String.valueOf(i);
                address = InetAddress.getByName(currIP);
                if (address.isReachable(5))
                {
                    iplan.addElement(address.getHostAddress());
                } 
                }
                catch (IOException e) { 
                     msgbox(ex.Message);
                }
                
                
            } 
            msgbox("Fine ricerca!");
        } 
        catch (UnknownHostException ex) {
            msgbox(ex.Message());
        }

mi produce in output solo:

192.168.1.100
192.168.1.101

quando invece gli altri due IP sono pingabili:

ping -t 3 192.168.1.102
PING 192.168.1.102 (192.168.1.102): 56 data bytes
64 bytes from 192.168.1.102: icmp_seq=0 ttl=128 time=2.936 ms
64 bytes from 192.168.1.102: icmp_seq=1 ttl=128 time=11.346 ms
64 bytes from 192.168.1.102: icmp_seq=2 ttl=128 time=2.913 ms


--- 192.168.1.102 ping statistics ---
3 packets transmitted, 3 packets received, 0.0% packet loss
round-trip min/avg/max/stddev = 2.913/5.732/11.346/3.970 ms

e

ping -t 3 192.168.1.254
PING 192.168.1.254 (192.168.1.254): 56 data bytes
64 bytes from 192.168.1.254: icmp_seq=0 ttl=254 time=2.094 ms
64 bytes from 192.168.1.254: icmp_seq=1 ttl=254 time=2.316 ms
64 bytes from 192.168.1.254: icmp_seq=2 ttl=254 time=2.228 ms

--- 192.168.1.254 ping statistics ---
4 packets transmitted, 3 packets received, 25.0% packet loss
round-trip min/avg/max/stddev = 2.094/2.213/2.316/0.091 ms

Come mai?
In cosa sbaglio?