GW OS 4.2.0 UDP forwarder to TTN - no downlinks

I switche to v4 a few weeks ago and move my gateway to 4.2 gateway OS a few days later.
On the old version I had the packet forwarder running and pushed packets to TTN. I created the gateway in TTN and I looked good, TTN got packets and status from the gateway. But I never tested it with a real device.
Now I wanted to do so with v4, the gateway was still liste connected and ok with the correct configured UDP packet forwareder. Also a device could send packate to TTN but the downlinks do not work.
I analyzed the network traffic and it seems everythin is fine, the UDP packets come back from TTN and are routed to my gateway throught my firewall but it seems they are not processed correctly.
But I am unable to find any log or something on the gateway, the config for the UDP forwarder says it logs to syslog, but there are any messages from it there.

Any ideas?

You could use logread -f -l 100 -e chirpstack-udp-forwarder to read the UDP Forwarder logs. Does this show anything relevant?

This does not return anything.
I had the forwarder up since my initial post, I have no active devices in appllications on TTN but TTN shows the gateway connected as it always did and packets are received by TTN. I see the packets from my devices I manage on my Chirpstack server so. But as TTN does not know them, there is no communication back from TTN to the gateway.

Is it nomal that the UDP forwarder does not log anything?

The service is running:

22210 root     13348 S    /usr/bin/chirpstack-udp-forwarder -c /var/etc/chirpstack-udp-forwarder/chirpstack-udp-forwarder.toml

The configuration is this:



I didn’t manually interfere, I just used the webinterface…

Ok I did a few tests again and it seems downlinks work.
The device reacts to ADR messages and downlinks with configuration changes also do what they should.
Although there seems no difference between unconfirmed and confirmed downlinks, that may be related to the error I get, TTN logs “Downlink transmission failed with result UNKNOWN_ERROR”.
So as far as I can tell TTN get the uplink data, transmits the downlinks but does not get a correct result from the gateway that the downlink has been processed correctly.

And I don’t have any logs entries of the UDP forwarder in GatewayOS