Happening intermittent, 3/5 executions are SUCCESS, 2 are getting failed with below error.

In our UAT environment facing below error once in a while, Any suggestion how to fix?

CODE:

  BoxDeveloperEditionAPIConnection  boxConnection = new BoxDeveloperEditionAPIConnection(EnterpriseId(), DeveloperEditionEntityType.ENTERPRISE, boxConfig, null); 

Proxy   proxy = new Proxy(Proxy.Type.HTTP, new InetSocketAddress(proxy-uat.apple.com, 8080));
  boxConnection.setProxy(proxy);
boxConnection.authenticate();

ERROR:

com.box.sdk.BoxAPIException: Couldn't connect to the Box API due to a network error

at com.box.sdk.BoxAPIConnection.executeOnClient(BoxAPIConnection.java:1259) ~1box-java-sdk-4.0.1.jar:?]

Caused by: java.io.IOException: Unexpected response code for CONNECT: 403