KNX/IP Interface Individual Address ignored

For testing I’ve changed the localSourceAddr to something not configured for Weinzierl interface:

UID: knx:ip:c6aa14dc5d
label: KNX/IP Gateway
thingTypeUID: knx:ip
configuration:
  useNAT: false
  readRetriesLimit: 3
  ipAddress: 192.168.66.xxx
  autoReconnectPeriod: 60
  type: TUNNEL
  localSourceAddr: 15.15.245
  readingPause: 50
  portNumber: 3671
  responseTimeout: 10

But the result is the same, telegrams are coming from different address (which I can’t explain fully now):

and OH logs still contain the exception:

23:12:58.153 [WARN ] [.internal.handler.DeviceThingHandler] - An error occurred on channel knx:device:c6aa14dc5d:KNXDateTime:DateTime: no confirmation reply received for 15.15.245->0/4/0 L_Data.req, low priority hop count 6 repeat, tpdu 00 80 79 08 10 17 0c 33 24 00
tuwien.auto.calimero.KNXTimeoutException: no confirmation reply received for 15.15.245->0/4/0 L_Data.req, low priority hop count 6 repeat, tpdu 00 80 79 08 10 17 0c 33 24 00

And if the screenshot of the Weinzierl interface doesn’t show addresses that the IP-side clients should use, then I probably don’t get their manual at all:

For the interface function the device contains additional individual addresses that can be set in the ETS (ETS 4.2 or higher).
When a client (e.g. ETS) sends via the KNX IP Interface telegrams to the bus, they contain a sender address as one from the
additional addresses
. Each address is associated with a connection. Thus response telegrams can be clearly transmitted to the
respective client.
The additional individual addresses must be selected from the
address range of the bus line in which the interface is installed
and may not be used by another device.
Example:
Device address 1.1.10 (address within ETS topology)
Connection 1 1.1.250 (1. additional address)
Connection 2 1.1.251 (2. additional address)
Connection 3 1.1.252 (3. additional address)
Connection 4 1.1.253 (4. additional address)
Connection 5 1.1.254 (5. additional address)
Section “Individual Address” enables you to change the individual KNX address of the currently used KNXnet/IP Tunneling
connection.

How would you interpret that?
The configuration on my screetshot shows that addresses starting with 15.15.250 are the additional addresses (note the indentation).