Weinzierl 762 not working in ROUTER mode


I’m having issues in configuring my Weinzierl 762 Linemaster in ROUTER mode. If I try the TUNNEL setup it works flawlessly.
Openhab 2.4 runs on a FreeBSD 12.0-RELEASE-p3. The /16 network has no routers between the devices. Openhab is on machine The dhcp server is setup to assign to the Weinzierl. I’m using ETS inside and I programmed the interface to “route”, “acknowledge” and “repeat” everything and it’s address is 12.0.0. I checked my network router that it was not filtering any multicast traffic. I removed any such filter on the FreeBSD’s own firewall as well.

My .things config:

Bridge knx:ip:bridge "Weinzierl KNX IP LineMaster 762" [
] {
	Thing device bin5 "DATEC 4x Out 8x In" @ "H2 Dining" [
    ] {
    	Type contact : H2_Living_Window1		"H2 Living Window 1"	[ ga="1.009:<0/5/2" ]
    	Type contact : H2_Living_Window2		"H2 Living Window 2"	[ ga="1.009:<0/5/0" ]
    	Type contact : H2_Living_Window3		"H2 Living Window 3"	[ ga="1.009:<0/5/1" ]
    	Type contact : H2_Living_Door			"H2 Living Door"		[ ga="1.009:<0/5/3" ]
    	Type contact : H2_Living_Motion			"H2 Living Motion"		[ ga="1.009:<0/5/11" ]
    	Type contact : H2_Dining_Motion			"H2 Dining Motion"		[ ga="1.009:<0/5/8" ]

When I turn everything on PaperUI shows the bridge immediately online but not the “bin5” device of the configuration.

Telegrams from the KNX bus seem to work fine. To test it I activated a cyclical sending on the binary interface and as expected, every 60 seconds I see 6 packets with tcpdump in the form of:

IP (tos 0x0, ttl 16, id 214, offset 0, flags [none], proto UDP (17), length 45) > UDP, length 17

That is from the KNX router to the multicast address as I assume it is supposed to happen.

I can also see on the karaf console the six matching entries similar to:

[DEBUG] [x.internal.handler.DeviceThingHandler] - onGroupWrite Thing 'knx:device:bridge:bin5' received a GroupValueWrite telegram from '12.0.7' for destination '0/5/11'

The problem occurs in the opposite direction. No polling from openhab gets any reply from the KNX bus. My karaf log is full of:

[DEBUG] [knx.internal.client.AbstractKNXClient] - Could not read value for datapoint 0/5/11: timeout waiting for group read response from 0/5/11. Going to retry.

Looking at the tcpdump though I can see the packets running the other way in the form of:

IP (tos 0x0, ttl 1, id 39976, offset 0, flags [none], proto UDP (17), length 45) > UDP, length 17

(that is from openhab’s ip to the multicast address).

I’ve seen a lot of similar “router mode” related discussions but all seem to have a bunch of errors to work with. Mine simply seems to ignore the traffic from the net to the bus.

Am I missing something obvious? It’s my first setup so I’m pretty much clueless about a lot of things here.

Any help is kindly appreciated,