SymmetricDS client throws AuthenticationException

INFO  [client-001-job-3] o.j.s.s.impl.DataLoaderService - Using registration URL of http://localhost:8080/sync/server/registration?nodeGroupId=client&externalId=001&syncURL=http%3A%2F%2Flocalhost%3A8081%2Fsync%2Fclient-001&schemaVersion=%3F&databaseType=H2&databaseVersion=1.4&symmetricVersion=3.11.9&deploymentType=client&hostName=XXXXXXX&ipAddress=XX3
ERROR [client-001-job-3] o.j.s.s.impl.RegistrationService - Unexpected error during registration: org.jumpmind.symmetric.transport.AuthenticationException
org.jumpmind.symmetric.transport.AuthenticationException: null
	at org.jumpmind.symmetric.transport.http.HttpIncomingTransport.openStream(HttpIncomingTransport.java:139)
	at org.jumpmind.symmetric.transport.http.HttpIncomingTransport.openReader(HttpIncomingTransport.java:156)
	at org.jumpmind.symmetric.service.impl.DataLoaderService.loadDataFromTransport(DataLoaderService.java:592)
	at org.jumpmind.symmetric.service.impl.DataLoaderService.loadDataFromPull(DataLoaderService.java:302)
	at org.jumpmind.symmetric.service.impl.DataLoaderService.loadDataFromPull(DataLoaderService.java:258)
	at org.jumpmind.symmetric.service.impl.RegistrationService.attemptToRegisterWithServer(RegistrationService.java:505)
	at org.jumpmind.symmetric.service.impl.RegistrationService.registerWithServer(RegistrationService.java:481)
	at org.jumpmind.symmetric.service.impl.PullService.pullData(PullService.java:89)
	at org.jumpmind.symmetric.job.PullJob.doJob(PullJob.java:48)
	at org.jumpmind.symmetric.job.AbstractJob.invoke(AbstractJob.java:227)
	at org.jumpmind.symmetric.job.AbstractJob.run(AbstractJob.java:298)
	at org.springframework.scheduling.support.DelegatingErrorHandlingRunnable.run(DelegatingErrorHandlingRunnable.java:54)
	at java.base/java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:515)
	at java.base/java.util.concurrent.FutureTask.runAndReset(FutureTask.java:305)
	at java.base/java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:305)
	at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
	at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
	at java.base/java.lang.Thread.run(Thread.java:835)

I do not know why this symetricDS error occures.

I needed to register the clients /sync URL as well.

  @Bean
  public ServletRegistrationBean<SymmetricServlet> symServlet() {
    ServletRegistrationBean<SymmetricServlet> bean = new ServletRegistrationBean<>(new SymmetricServlet(), "/sync/*");
    bean.setLoadOnStartup(1);
    return bean;
  }