Can't get "delivered" event after successful delivering downlink message

[clafix]

Hi everyone!

I'm working with lorawan-server about a some weeks, and uplink messages from device works fine. I see "join" events and see correct uplink data in server web-interface (Frames) and in MQTT.fx client.

But publishing downlink messages wroks not as expected. I'm tried to send (publish) downlink messages from MQTT.fx client to device, and found 2 issues:

1. I can't get "delivered" event anyway (even if downlink message really delivered to device). But "lost" events i see as expected. Also, in publish message: "confirmed":true, "receipt" - presented; our lora device is device of Class A.
2. Downlink message successfuly delivering on device (and visible at server "Frames" screen) only, if publish will be fired immediately after device "join" event. Event "delivered" also don't firing here.

Proofs of this issue:

1. Publishing message before "join" event (delivery fails): After got uplink: Message to publish:
2. Publishing message after "join" event (delivery successful): After got uplink (and downlink): Connector screen:

This behaviour (fail delivery on publish before "join" and success delivery on publish immediately after "join") checked a lot of times. It really works as is. Event "delivered" i I have never seen at all testings time.

What i do wrong, and how i can get event "delivered"? And why message delivering successfuly, only if it will be sent only immediately after "join" (although the message is stored on the server until the "join" event)?

I would be grateful for any help, thanks in advance!

[clafix]

I also noticed that after a long time of work (1-2 days) the server stops accepting any published messages from mqtt clients. Messages do not appear in the device’s Downlinks, and the server even does not show an error if you send broken JSON. After the server container restart, publish starts working fine. Before container restart: After: