S3 Compatible Storage - The stream does not support concurrent IO read or write operations

Im trying to setup a Backup Job with a S3 compatible Storage, the connection is working fine but the upload fails with the following error:

Other posts with the same error had no solution, but it seems to be a S3 specific issue.
Duplicati Version is 2.0.6.3.

Any ideas?

  1. Febr. 2022 11:30: Failed while executing “Backup” with id: 6
    System.AggregateException: One or more errors occurred. —> System.AggregateException: The stream does not support concurrent IO read or write operations. —> System.NotSupportedException: The stream does not support concurrent IO read or write operations.
    at CoCoL.AutomationExtensions.d__101.MoveNext() --- End of stack trace from previous location where exception was thrown --- at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw() at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) at Duplicati.Library.Main.Operation.BackupHandler.<FlushBackend>d__19.MoveNext() --- End of stack trace from previous location where exception was thrown --- at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw() at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) at Duplicati.Library.Main.Operation.BackupHandler.<RunAsync>d__20.MoveNext() --- End of inner exception stack trace --- at Duplicati.Library.Main.Operation.BackupHandler.<RunAsync>d__20.MoveNext() --- End of inner exception stack trace --- at CoCoL.ChannelExtensions.WaitForTaskOrThrow(Task task) at Duplicati.Library.Main.Controller.<>c__DisplayClass14_0.<Backup>b__0(BackupResults result) at Duplicati.Library.Main.Controller.RunAction[T](T result, String[]& paths, IFilter& filter, Action1 method)
    at Duplicati.Library.Main.Controller.Backup(String[] inputsources, IFilter filter)
    at Duplicati.Server.Runner.Run(IRunnerData data, Boolean fromQueue)

I wonder if setting this might help:

--asynchronous-concurrent-upload-limit=1

What kind of S3 back end is this?