End-device missing ack downlinks

Hi guys

Using xDots with Multitech Conduit and the semtech packet forwarder with chirpstack installed in a low-latency region.

the xdots are sending confirmed uplinks with 5 retires. In 20 uplink messages, I will have 5 retires at least.

What can be the cause do you think? Gateway is connected via ethernet. Using AU915 sub-band1

Any adjustments I can try in the network server configuration?

Hi Tom,

Couple thoughts from what I’ve experienced: Are you using ADR? What’s the signal quality like on uplinks? Are you aware of any other RF that may be competing (e.g. RFID)?

There is a bug I believe with data rate 4 that can cause downlinks to be missed if the devices are too close to the gateway. I have the network server set to max DR of 3


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… this could be the solution to my problems with two sensors, that stopped working about 7 days ago.
They are sending confirmed up but no response with an ack after two retries. I will try max DR = 3.

@John_Roesler thanks for your suggestions, we had buggy firmware. The xDot was set to do 5 retires on the ACK, but the MCU was not waiting long enough for the xDot to finish before it attempted again, which resulted in a slew of uplinks, and not enough time for downlinks.

something like that, anyway new developers did a much better job, they cancel the xdot retire mechanism all together and set it in the MCU level only.

But also I know what you mean and had that happen to me as well.

Hi @Tom_Z can you show me your config file? from chirpstack-network-server.toml
I think it might be something in his configuration!