use system preference to choose between ipv4 and ipv6 addresses from a host which offers both

build.gradle

@@ -127,7 +127,7 @@ test {
 }
 
 run {
-    applicationDefaultJvmArgs = ["-XX:+HeapDumpOnOutOfMemoryError",
+    applicationDefaultJvmArgs = ["-XX:+HeapDumpOnOutOfMemoryError", "-Djava.net.preferIPv6Addresses=system",
                                  "--add-opens=javafx.graphics/com.sun.javafx.css=org.controlsfx.controls",
                                  "--add-opens=javafx.graphics/javafx.scene=org.controlsfx.controls",
                                  "--add-opens=javafx.controls/com.sun.javafx.scene.control.behavior=org.controlsfx.controls",
@@ -173,7 +173,8 @@ jlink {
     options = ['--strip-debug', '--compress', '2', '--no-header-files', '--no-man-pages', '--ignore-signing-information', '--exclude-files', '**.png', '--exclude-resources', 'glob:/com.sparrowwallet.merged.module/META-INF/*']
     launcher {
         name = 'sparrow'
-        jvmArgs = ["--add-opens=javafx.graphics/com.sun.javafx.css=org.controlsfx.controls",
+        jvmArgs = ["-Djava.net.preferIPv6Addresses=system",
+                   "--add-opens=javafx.graphics/com.sun.javafx.css=org.controlsfx.controls",
                    "--add-opens=javafx.graphics/javafx.scene=org.controlsfx.controls",
                    "--add-opens=javafx.controls/com.sun.javafx.scene.control.behavior=org.controlsfx.controls",
                    "--add-opens=javafx.controls/com.sun.javafx.scene.control.inputmap=org.controlsfx.controls",