Configuring Class-C (RX2) downlink parameters

i use this command to send downlink from lora server to my node:
mosquitto_pub -h localhost -t “application/1/node/1111111111111111/tx” -u user -P user -m ‘{“reference”: “abcd”,“freq”:868.1, “confirmed”: false, “fPort”:7, “data”: “aGVsbG8=”}’

and i get this on server and same on the gateway:

Can i change default “frequency” from 869525000 to 868100000 and “spreadFactor” from 12 to 7 and send downlnk with this settings?

It looks like your device is configured as a Class-C device. For Class-C, RX2 parameters are used. For ABP devices initially the values are taken from the device-profile. However LoRa Server will re-configure your devices using the values configured in your loraserver.toml configuration file. Please see:

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Thank you for reply)
Yes, my device is a Class-C device. I have “EU_863_870” band configuration.
Accroding to this: i have tried to set up rx2 parameters like this:

But it hasn’t changed anything for me) What have i made wrong?

Before the network-server will use these values, it first needs to notify the device and receive an acknowledgement on that change. An uplink message from your device should trigger LoRa Server to send the related Mac-commands.

As i have understood you, when i use this mqtt command - downlink shall go to the queue(on server) and have to be sent only after some uplink will come from node, right?) But in my cause - this downlink send to my gateway right after this mqtt command. And frequancy still 869525000, spreadFactor - 12

Interesting thing. I changed device class from C to B, and when i used my mqtt command i got downlink on my node for the first time) And on server frame logs i get nothitg during this operation (no downlink).

Yes, but as your device did send data before, LoRa Server will send the data immediately as it knows which gateway to use. Note that when your devices is configured as an OTAA device, LoRa Server assumes that your device uses 869525000 as its default RX2 frequency.

Changing your device to Class-B means that before operating as a Class-B device, your device must first acquire a GPS beacon lock. Until then it is considered as a Class-A device.

Well, thank you very much for your replies) i will continue to understand the logic of work)
This topic can be closed.

@mir did you get it working, I have been looking for mac command that can be sent in downlink to change the frequency and spread factor, when the device is in operation. Thanks.

I have this exact problem. frequency and SF is never changing. do you remember how you managed to resolve the issue?