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Java RMI cannot connect to server via WAN while it works in LAN

I'm working on a project using Java RMI and with a client-server implementation.
On the server side, this is how I initialize my server:
final String url = "localhost";
final int port = 8090;
LocateRegistry.createRegistry(port);
IServerGame serverGame = new ServerGame();
Naming.rebind("//"+url+":"+port+"/undercover", serverGame);
System.out.println("Server running at //" + url + ":" + port + "/undercover")
Undercover is the name of my application. We chose to use the port 8090
arbitrarily.
Now, here is how I initialize the connection client-side:
try {
server = (IServerGame) Naming.lookup("//"+address+":8090/undercover");
System.out.println("Connected to server " + address + ".");
} catch (Exception e) {
System.out.println("Connection failed.");
e.printStackTrace();
}
address is a string in the parameter of the method which initializes the connection and is the IP of the server. We ask the client to enter this IP to allow us to connect to different servers if we want.
When I run my application in local, whether I use localhost or my private IP 192.168.x.x as address, everything works fine. The client connects to the server and I can use the application. The problem is that when I want to use the application via WAN, sending the client to a friend and starting the server on my local machine, it doesn't work anymore. I get this error:
java.rmi.ConnectException: Connection refused to host: (private IP of host machine); nested exception is:
java.net.ConnectException: Connection timed out: connect
I've already checked a lot of posts in StackOverflow with the exact same problem and the usual answer is to either set the SystemProperty(java.rmi.server.hostname,"192.168.x.x") or do it via the -Djava.rmi.server.hostname in command line. I'm using Gradle to compile. I run the application via the run task. The client is a basic fx application too. None of this works unfortunately. I've also tried to open the port 8090 in my firewall but it doesn't solve the problem either.
Now maybe I'm doing this wrong. I've also tried to replace my private IP 192.168.x.x, which is IPv4 that I found via ipconfig in the command shell, with my public IP 79.95.x.x. But, again, it doesn't work.
I tried adding the SystemProperty(java.rmi.server.hostname,"192.168.x.x") like the first line of code that appears in the server code I showed you above.
I'm connected to internet via 4G. I don't have a box connection, so I can't really go to the box settings to allow certain ports, if that's ever a thing that could fix the issue.
EDIT :
So i've tried to switch from naming implementation in server-side to Registry implementation as it was suggested bellow but it didn't make any difference. As i thought it could be just a connection problem, i asked a friend to ping the server with telnet on the port 8090 and in fact it didn't work. He ran telnet [domain name or ip] [port] and the error was :
Unable to connect to remote host: Connection timed out
So the problem is that the external clients cannot reach my server or connect to the port. As i'm using 4G as internet connection as i mentioned above, any idea on how i could make the port reachable ?

Try using class java.rmi.registry.Registry rather than class java.rmi.Naming.
On the server side:
final int port = 8090;
Registry registry = LocateRegistry.createRegistry(port);
ServerGame serverGame = new ServerGame();
IServerGame stub = (IServerGame) UnicastRemoteObject.exportObject(serverGame, 0);
registry.bind("undercover", stub);
On the client side:
Registry registry = LocateRegistry.getRegistry("server host name or IP", 8090);
IServerGame serverGame = (IServerGame) registry.lookup("undercover");

Java RMI connection error: Not connecting to localhost

I am trying to connect to my localhost when running my application, but for some reason it tries to connect to an ip address other than my localhost.
Below is the error message I am getting.
error
I have looked at my hosts file and is mapped like below:
hostsfile

As you are manually creating the Registry you could change the line 14 and 17 to
Registry registry = LocateRegistry.createRegistry(1099);
registry.bind("fileService", fs);
On the other hand Naming.rebind suppose to default the host to localhost but you could specify it anyway
Naming.rebind("//localhost/fileService", fs)
thought in that case the line with LocateRegistry.createRegistry is not necessary

Socket IO - how to configure and connect to netty socket io server on a secure domain

I need some help with doing netty socket io over https. I have got it to in my local env but not on a server with secure domain. The server starts but client isn't able to connect. Tried by starting the socket server with IP as well as domain name. For the server to start with domain name as hostname value in setHostname method, I added an entry in /etc/hosts file as following
127.0.0.1 localhost example.com
Socket server started by giving example.com as hostname but client isn't able to connect using the same hostname over https as following
var socket = io.connect('https://example.com:10443')
Tried with options - { secure: true, reconnect: true, rejectUnauthorized : false } too but the same issue.
On server side my configuration is as following
Configuration configuration = new Configuration();
configuration.setHostname("example.com");
configuration.setPort(10443);
configuration.setKeyStorePassword("mypassword");
InputStream stream = getClass().getClassLoader().getResourceAsStream("keystore.jks");
configuration.setKeyStore(stream);
The jsk file was created using keytool command for the same domain (example.com)
Is there something more to be done for the port - 10443 to be used by the socket server? Or is there any other configuration to be done?

Got the solution! I had not mentioned that the domain was set up on cloudflare. Here the issue was with the port I used - 10443. It's not supported by cloudflare. Changed it to 8443 and it worked!
For those who come across this, please find here the list of supported ports that Cloudflare work with. May save much of your time unlike me.
Also, please note that I used my public IP as hostname in setHostname() method so that I don't need anything added in my hosts file. Then gave the actual domain name with https on client side to connect to the server. That's it. Thank you all!
Sandeep

JMX Client for Zookeeper

I am trying to workout a JMX Java client for Zookeeper instance for a custom monitoring web app. As provided in document, Zookeeper provides various statistics through JMX MBeans.
For the excercise, I am running Zookeeper intance locally in standalone mode on Windows 7 Enterprise using following arguments:-
-Dcom.sun.management.jmxremote
-Dcom.sun.management.jmxremote.ssl=false
-Dcom.sun.management.jmxremote.local.only=false
-Dcom.sun.management.jmxremote.authenticate=false
-Dcom.sun.management.jmxremote.port=10010
-Dzookeeper.jmx.log4j.disable=false
After running my zookeeper intance, I am able to connect to JMX beans using JConsole that correctly shows all the statistics :-
PROBLEM
While trying to connect using my own code I am getting java.net.ConnectException: Connection refused: connect error. Code that I am trying :-
public static void main(String[] args) throws Exception {
// service:jmx:rmi:///jndi/rmi://#{host}:#{port}/jmxrmi
JMXServiceURL url = new JMXServiceURL("service:jmx:rmi:///jndi/rmi://localhost:10010/jmxrmi");
// This throws java.net.ConnectException !!!
JMXConnector jmxConnector = JMXConnectorFactory.connect(url);
MBeanServerConnection mbeanServerConnection = jmxConnector.getMBeanServerConnection();
ObjectName mbeanName = new ObjectName("org.apache.ZooKeeperService:name0=StandaloneServer_port2181");
ZooKeeperServerMXBean newProxyInstance = MBeanServerInvocationHandler.newProxyInstance(mbeanServerConnection,
mbeanName, ZooKeeperServerMXBean.class, true);
System.out.println("Created zoo mbean proxy");
System.out.println(newProxyInstance.getAvgRequestLatency());
}
Facing same problem while trying to connect using Java Visual VM.
What is the correct way to connect to Zookeeper MBean using Java code ?
UPDATE 1
There is 4 years old unresolved JIRA ticket that seems to be saying that there are two kind of ports that comes into play - jmx port & rmi port. The rmi port is generated randomly & I guess that is what needed while creating connection.
But then how JConsole is able to connect ?
UPDATE 2
This blog says that talking to remote JMX server over RMI protocol might be problem and suggests using JMXMP (JMX-Messaging Protocol) instead.
Now how do I exactly do I do that ?

post message to a remote JMS provider

I want to be able to send messages to a remote JBoss server (JBoss MQ).
I can do it for a local one but i'm stuck when trying with a remote one.
can anyone explain to me how to do it ?
are there any specific steps to take ?
[what i've tried so far]
I need to send a message to a remote server's queue (running "JBoss MQ") so that it can process the message and act on it.
Properties properties = new Properties();
properties.put(Context.INITIAL_CONTEXT_FACTORY, "org.jnp.interfaces.NamingContextFactory");
properties.put(Context.URL_PKG_PREFIXES, "org.jnp.interfaces");
properties.put(Context.PROVIDER_URL, "jnp://192.168.131.129:1299");
InitialContext jndiContext = new InitialContext(properties);
//[2] Look up connection factory and queue.
ConnectionFactory connectionFactory = (ConnectionFactory)jndiContext.lookup("UIL2XAConnectionFactory");
Queue queue = (Queue)jndiContext.lookup("Queue/DataTransferQueue");
but I get an exception when running the above code :
(even though, I can ping the remote server).
javax.naming.CommunicationException: Could not obtain connection to any of these urls: 192.168.1.131.129:1299 and
discovery failed with error: javax.naming.CommunicationException:
Receive timed out [Root exception is java.net.SocketTimeoutException: Receive timed out]
[Root exception is javax.naming.CommunicationException: Failed to connect to server 192.168.1.131.129:1299
Is there anything special to do to connect to a remote queue ?

Have you verified that you can connect to that remote host and port, i.e. telnet 192.168.131.129 1299? You might have a firewall that's blocking some traffic but allowing pings.

OK, so after trying a lot, I finally found out what the problem was :
I didn't start JBoss on the remote server in a way it could accept remote connections. by default, JBoss starts allowing only local connections.
so, I restarted it with this argument : -b 0.0.0.0 and it works fine now.
Thanks for your help and support.