Milo OPCUA Client times out waiting for secure channel - eclipse

Question

I am developing a service for Apache NiFi which is supposed to be able to Subscribe to a few variables on an OPCUA server. I can't get the service to connect to the OPCUA server. This is the stacktrace:
java.util.concurrent.ExecutionException: UaException: status=Bad_Timeout, message=timed out waiting for secure channel
at java.util.concurrent.CompletableFuture.reportGet(CompletableFuture.java:357)
at java.util.concurrent.CompletableFuture.get(CompletableFuture.java:1895)
at com.hashmapinc.tempus.processors.StandardMiloOPCUAService.createClient(StandardMiloOPCUAService.java:75)
at com.hashmapinc.tempus.processors.StandardMiloOPCUAService.onEnabled(StandardMiloOPCUAService.java:92)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.apache.nifi.util.ReflectionUtils.invokeMethodsWithAnnotations(ReflectionUtils.java:137)
at org.apache.nifi.util.ReflectionUtils.invokeMethodsWithAnnotations(ReflectionUtils.java:125)
at org.apache.nifi.util.ReflectionUtils.invokeMethodsWithAnnotations(ReflectionUtils.java:70)
at org.apache.nifi.util.ReflectionUtils.invokeMethodsWithAnnotation(ReflectionUtils.java:47)
at org.apache.nifi.controller.service.StandardControllerServiceNode$2.run(StandardControllerServiceNode.java:400)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$201(ScheduledThreadPoolExecutor.java:180)
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:293)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at java.lang.Thread.run(Thread.java:748)
Caused by: org.eclipse.milo.opcua.stack.core.UaException: timed out waiting for secure channel
at org.eclipse.milo.opcua.stack.client.handlers.UaTcpClientMessageHandler.lambda$handlerAdded$2(UaTcpClientMessageHandler.java:151)
at io.netty.util.HashedWheelTimer$HashedWheelTimeout.expire(HashedWheelTimer.java:581)
at io.netty.util.HashedWheelTimer$HashedWheelBucket.expireTimeouts(HashedWheelTimer.java:655)
at io.netty.util.HashedWheelTimer$Worker.run(HashedWheelTimer.java:367)
... 1 common frames omitted
So it's timing out while waiting for a secure channel. When I supply some bogus IP address to the service, it just says that the connection timed out.
This is the code I use to create the client:
private OpcUaClient createClient() throws Exception {
EndpointDescription[] endpoints;
endpoints = UaTcpStackClient
.getEndpoints("opc.tcp://theaddress:49320")
.get();
EndpointDescription endpoint = endpoints[0];
OpcUaClientConfig config = OpcUaClientConfig.builder()
.setApplicationName(LocalizedText.english("MinimalClient"))
.setApplicationUri("urn:theurn")
.setCertificate(null)
.setKeyPair(null)
.setEndpoint(endpoint)
.setMaxResponseMessageSize(uint(50000))
.setIdentityProvider(new AnonymousProvider())
.setRequestTimeout(uint(5000))
.build();
return new OpcUaClient(config);
}
Could this be a firewall issue? Does it connect to the server and then fails to get a secure channel? FYI: The server allows anonymous identity and has SecurityPolicy: NONE.