Setting SNR margin for selecting gateway for transmitting ACK

I understand that the networkserver will randomly choose which gateway to use for transmitting acknowledgment to a device, from the list of gateways that have a SNR above a certain threshold (and use the gateway with the best SNR, if none of the gateways are above the threshold).

But is it possible to configure this threshold? It appears that their should be a parameter called “gateway_prefer_min_margin” which should handle this. I can however not find this variable in the .toml file?

I appreciate any help.

It is not random. When received from multiple gateways, the network server will reply via the one with the strongest signal. To my knowledge, this is not configurable.

I have not been able to find any documentation that describes this. But in the source code at: it seems that a random gateway is selected among the gateways that have received the frame with a SNR grater than the threshold.

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Ah, perhaps I’m working from old information. I can see that being useful for load balancing.

I have not seen any discussion of customizing it.

Looks like it would go in the [] section of a region.toml

@Jason_Reiss is correct. The default is 10, meaning that ChirpStack will pick a random gateway from the gateways that have a link-margin of > 10 (to make sure that download load is spread across multiple gateways).

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