KNX Interface (MDT IP Interface) stops to work with Home Assistant

Third party integrations
1

Dear all,

from time to time I face the issue, that my MDT IP Interface for accessing KNX bus, stops to work. I reserved four different tunnels (1.1.1-1.1.4) in ETS, which are working quite good. In daily life, only one tunnel is active (Home Assistant).

Today again, the interface stops to work. No reading/writing to the bus was possible:

I found those lines from error log


2025-11-21 17:54:29.579 DEBUG (MainThread) [xknx.ga_dpt] No transcoder found for DPTs: {"{'main': 1, 'sub': None}"}
2025-11-21 17:54:29.580 DEBUG (MainThread) [homeassistant.components.knx.project] Loaded KNX project data with 328 group addresses from storage
2025-11-21 17:54:29.582 DEBUG (MainThread) [homeassistant.components.knx.storage.config_store] Loaded KNX config data from storage. 2 entity platforms
2025-11-21 17:54:29.583 INFO (MainThread) [xknx.log] XKNX v3.10.1 starting tunneling_tcp connection to KNX bus.
2025-11-21 17:54:29.653 DEBUG (KNX Interface) [xknx.log] Starting tunnel to 192.168.178.4:3671 over TCP requesting individual address 1.1.3
2025-11-21 17:54:32.729 DEBUG (KNX Interface) [xknx.log] Could not establish connection to KNX/IP interface. OSError: [Errno 113] Connect call failed ('192.168.178.4', 3671)

After power-cylcing the interface device, everything is working as expected. Does anyone has an idea, how this situation can be solved? Is this Home Assistant related, or MDT Firmware, or MDT hardware?

2

Sadly this is an ongoing problem with MDT interfaces/routers. Specially with secure, but also happens on non-secure connections.

Just search the forums and you will find a lot of examples of this.

Best way is to get another brand interface for now, they are all roughly the same price.

I tend to stick with either Gira, Jung or Weinzierl

3

Hi :wave:!

OSError: [Errno 113]

Means “No route to host”. This is most probably a network issue.

4

You are right. But my complete Network is doing fine. So the MDT ip interface seems to have a network issue?! Does anyone have similar problems?
In thr German knx user community several guys claims to have a problem since HA 2026.10

5

I wouldn’t be surprised by that - this device has some known bugs… but this would be new.
Since the error you are receiving isn’t at all KNX related, but a pure OS / network error, I wouldn’t bet on the network “doing fine”. Things can break - even without any changes.
Anyway, maybe try to change LAN cables for the device - could just be a bad cable.