KNX2 disconnected not gracefully (timeout)

Good evening everybody,

since a couple of weeks I’m running the KNX2 layout, since updating to the scheme I’m faced with the following message in the openhab.log:

2019-01-06 22:13:57.224 [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) [?:?]

Where does this come from?

many thanks.