General Question about Queuing


As I still have problems with sending Class-C Downlinks (it often takes minutes until receiving txack) I am wondering where messages will be queued?

Is it only on Chirpstack NS site or also direct on Gateway site?
Currently I read a post here regarding rx1 delay time. Within the post someone explained that rx1 delay time will be send to Gateway so that the Gateway queue the packet until the time to transmit.


The RX1 Delay is relevant to Class-A, not C (it defines the delay between the uplink and the downlink receive-windows).

Most likely, the downlink is in your case in the ChirpStack downlink queue. I’m not sure what is causing your issue as there are many different things that could cause a delay.

For example when you are using confirmed downlinks, then ChirpStack will keep the item in the queue until it has been acknowledged by your device, or until the Class-C timeout has occurred (configured in the device-profile).

Hi brocaar,
I tried with confirmed an non confirmed downlinks.
Sometimes it works immediately. Sometimes it took minutes until txack.
In the attached example I send the downlink at 14:02.
The txack comes at 14:04. There are 2 minutes between putting the command in the queue and getting the txack. I made several tests. Sometimes it tooks even >5 minutes.
As soon as I get the txack the queue is empty.
What other different things could cause the delay you mentioned?