KNX2 warning in openhab.log

Hello community,

I’m struggeling since the migration to KNX2 binding with the following issue and couldn’t find any solution for it:
(the actual version is running - openHAB 2.4.0 Release Build)

2019-01-16 17:47:47.509 [WARN ] [calimero.mgmt.TL 192.168.2.251:3671 ] - disconnected not gracefully (timeout)
tuwien.auto.calimero.KNXTimeoutException: no confirmation reply received for 1.1.9->1.1.1 L_Data.req, system priority hop count 6 repeat, tpdu 81
at tuwien.auto.calimero.knxnetip.ClientConnection.doExtraBlockingModes(ClientConnection.java:244) ~[?:?]
at tuwien.auto.calimero.knxnetip.ConnectionBase.send(ConnectionBase.java:258) ~[?:?]
at tuwien.auto.calimero.knxnetip.KNXnetIPTunnel.send(KNXnetIPTunnel.java:178) ~[?:?]
at tuwien.auto.calimero.link.KNXNetworkLinkIP.onSend(KNXNetworkLinkIP.java:243) ~[?:?]
at tuwien.auto.calimero.link.AbstractLink.send(AbstractLink.java:351) ~[?:?]
at tuwien.auto.calimero.link.KNXNetworkLinkIP.sendRequestWait(KNXNetworkLinkIP.java:222) ~[?:?]
at tuwien.auto.calimero.mgmt.TransportLayerImpl.sendDisconnect(TransportLayerImpl.java:612) ~[?:?]
at tuwien.auto.calimero.mgmt.TransportLayerImpl.disconnectIndicate(TransportLayerImpl.java:600) ~[?:?]
at tuwien.auto.calimero.mgmt.TransportLayerImpl.disconnect(TransportLayerImpl.java:342) ~[?:?]
at tuwien.auto.calimero.mgmt.Destination.destroy(Destination.java:371) ~[?:?]
at tuwien.auto.calimero.mgmt.Destination.close(Destination.java:383) ~[?:?]
at tuwien.auto.calimero.mgmt.ManagementProceduresImpl.isAddressOccupied(ManagementProceduresImpl.java:311) ~[?:?]
at org.openhab.binding.knx.internal.client.AbstractKNXClient.isReachable(AbstractKNXClient.java:338) ~[?:?]
at org.openhab.binding.knx.handler.AbstractKNXThingHandler.pollDeviceStatus(AbstractKNXThingHandler.java:144) ~[?:?]
at org.openhab.binding.knx.handler.AbstractKNXThingHandler.lambda$1(AbstractKNXThingHandler.java:184) ~[?:?]
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511) [?:?]
at java.util.concurrent.FutureTask.runAndReset(FutureTask.java:308) [?:?]
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$301(ScheduledThreadPoolExecutor.java:180) [?:?]
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:294) [?:?]
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) [?:?]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) [?:?]
at java.lang.Thread.run(Thread.java:745) [?:?]

Any proposals for me?

many thanks in advance