Attempt to open the listen port (default 12392) using UPnP, if the local network supports it.

src/main/java/org/qortal/network/Network.java

@@ -1,5 +1,6 @@
 package org.qortal.network;
 
+import com.dosse.upnp.UPnP;
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
 import org.bouncycastle.crypto.params.Ed25519PrivateKeyParameters;
@@ -183,6 +184,11 @@ public class Network {
             }
         }
 
+        // Attempt to set up UPnP. All errors are ignored.
+        if (Settings.getInstance().isuPnPEnabled()) {
+            UPnP.openPortTCP(Settings.getInstance().getListenPort());
+        }
+
         // Start up first networking thread
         networkEPC.start();
     }

src/main/java/org/qortal/settings/Settings.java

@@ -181,6 +181,8 @@ public class Settings {
 	private boolean isTestNet = false;
 	/** Port number for inbound peer-to-peer connections. */
 	private Integer listenPort;
+	/** Whether to attempt to open the listen port via UPnP */
+	private boolean uPnPEnabled = true;
 	/** Minimum number of peers to allow block minting / synchronization. */
 	private int minBlockchainPeers = 5;
 	/** Target number of outbound connections to peers we should make. */
@@ -629,6 +631,10 @@ public class Settings {
 		return this.bindAddress;
 	}
 
+	public boolean isuPnPEnabled() {
+		return this.uPnPEnabled;
+	}
+
 	public int getMinBlockchainPeers() {
 		return this.minBlockchainPeers;
 	}