When Start android Simulator for React Native code, may be we meet this error: Starting JS server... Building and installing the app on the device (cd android && ./gradlew installDebug)... Downloading https://services.gradle.org/distributions/gradle-2.4-all.zip Exception in thread "main" java.net.ConnectException: Connection refused at java.net.PlainSocketImpl.socketConnect(Native Method) at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:345) at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:206) at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:188) at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392) at java.net.Socket.connect(Socket.java:589) at sun.security.ssl.SSLSocketImpl.connect(SSLSocketImpl.java:649) at sun.security.ssl.BaseSSLSocketImpl.connect(BaseSSLSocke...