Hi everyone,
I’ve been running OpenHAB for a long time and recently upgraded to OH 4.2.1 (also running for month now without issues). However, I’ve started experiencing severe issues with the KNX binding, and it’s now basically not working anymore.
Issue:
- OpenHAB reports timeouts when trying to communicate with the MDT SCN-IP.02 KNX/IP Router.
- The MDT router itself also experiences ping timeouts while OpenHAB is active.
- This was working fine before, and I haven’t changed my KNX setup recently.
2025-03-16 22:38:29.970 [INFO ] [nx.internal.client.AbstractKNXClient] - Bridge knx:ip:eb4d9731c0 connected to KNX bus
2025-03-16 22:38:36.976 [WARN ] [net/IP Tunneling 192.168.178.28:3671] - response timeout waiting for confirmation
tuwien.auto.calimero.KNXTimeoutException: no confirmation reply received for 0.0.0->1.0.210 L_Data.req, system priority hop count 6 repeat, tpdu 80
at tuwien.auto.calimero.knxnetip.ClientConnection.doExtraBlockingModes(ClientConnection.java:272) ~[?:?]
at tuwien.auto.calimero.knxnetip.ConnectionBase.send(ConnectionBase.java:268) ~[?:?]
at tuwien.auto.calimero.knxnetip.KNXnetIPTunnel.send(KNXnetIPTunnel.java:212) ~[?:?]
at tuwien.auto.calimero.link.KNXNetworkLinkIP.doSend(KNXNetworkLinkIP.java:514) ~[?:?]
at tuwien.auto.calimero.link.KNXNetworkLinkIP.onSend(KNXNetworkLinkIP.java:502) ~[?:?]
at tuwien.auto.calimero.link.AbstractLink.send(AbstractLink.java:406) ~[?:?]
at tuwien.auto.calimero.link.KNXNetworkLinkIP.sendRequestWait(KNXNetworkLinkIP.java:479) ~[?:?]
at tuwien.auto.calimero.mgmt.TransportLayerImpl.connect(TransportLayerImpl.java:332) ~[?:?]
at tuwien.auto.calimero.mgmt.TransportLayerImpl.sendData(TransportLayerImpl.java:351) ~[?:?]
at tuwien.auto.calimero.mgmt.ManagementClientImpl.send(ManagementClientImpl.java:1421) ~[?:?]
at tuwien.auto.calimero.mgmt.ManagementClientImpl.send(ManagementClientImpl.java:1270) ~[?:?]
at tuwien.auto.calimero.mgmt.ManagementClientImpl.sendWait(ManagementClientImpl.java:1359) ~[?:?]
at tuwien.auto.calimero.mgmt.ManagementClientImpl.sendWait(ManagementClientImpl.java:1430) ~[?:?]
at tuwien.auto.calimero.mgmt.ManagementClientImpl.readDeviceDesc(ManagementClientImpl.java:609) ~[?:?]
at tuwien.auto.calimero.mgmt.ManagementProceduresImpl.isAddressOccupied(ManagementProceduresImpl.java:432) ~[?:?]
at org.openhab.binding.knx.internal.client.AbstractKNXClient.isReachable(AbstractKNXClient.java:431) ~[?:?]
at org.openhab.binding.knx.internal.handler.DeviceThingHandler.pollDeviceStatus(DeviceThingHandler.java:508) ~[?:?]
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:539) [?:?]
at java.util.concurrent.FutureTask.runAndReset(FutureTask.java:305) [?:?]
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:305) [?:?]
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1136) [?:?]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:635) [?:?]
at java.lang.Thread.run(Thread.java:840) [?:?]
(Shortened for readability, full log available if needed.)
What I tried so far:
Restarted OpenHAB & KNX/IP Router
Verified the KNX/IP Router is reachable via ETS
Questions:
- Has anyone experienced similar issues with the MDT SCN-IP.02 router?
- Could OpenHAB be flooding the KNX bus, causing the router to overload?
- Are there any known issues with OH 4.2.1 and the KNX binding?
Any help or suggestions would be greatly appreciated! 
Thanks in advance! 