Class-C downlink latency

I am trying to achieve the lowest possible downlink latency.

I have a ChirpStack installation serving a single application to a single Class-C end-device.

The server, gateway and device are all configured to use the same frequencies. Power consumption is not an issue.

When pushing a downlink from the web-interface, it takes on average about 2.0 - 3.5 seconds for it to reach the device, even when the device is physically located about 1 meter from the gateway.

Is it possible to reduce this latency further?
What would be the right strategies / considerations to achieve this?

latency depends on which DR is used and payload size

Regarding data rate: I know that min_dr is set to 0, max_dr is set to 5 for all channels (default settings I believe) in both the network server and the device.

Regarding payload size, 3 bytes total.

Data is sent via the Chirpstack webinterface, I don’t know what DR is used and how I can influence it.

is your device use ADR ? in that case you can tune the DR margins in the service profile, or set the rx2_dr in the network-server .toml-file.
But it may prevent to shorten communication distance.

Thanks for the tip. I did have ADR enabled, and the end-device supports it.

Setting rx2 to 5 in the network-server.toml file helps. The message now takes 1.2 - 1.6 seconds on average.

The communication distance between device and gateway is only 1 meter (for these test circumstances).

Is this the fastest time that is feasible?