Cannot enable SF12BW125 on rak811

Issue: i’m trying to extend the transmition distance. So i configuate the datarate to the lowest. At this time only sf7,8,9,10 are available. As the lorawan region spec, i found that AS923 also support sf11 sf12 but when i set at+set_config=lora:dr:0, it respone the error 82.

Setup: AS923, adr on/off. Class C. channel 0,on,923200000,2,5; *1,on,923400000,2,5; *2,on,923600000,2,5; *3,on,923800000,2,5; *4,on,924000000,2,5; *5,on,924200000,2,5; *6,on,924400000,2,5; *7,on,924600000,2,5; 8,off,0,0,0; 9,off,0,0,0; 10,off,0,0,0; 11,off,0,0,0; 12,off,0,0,0; 13,off,0,0,0; 14,off,0,0,0; 15,off,0,0,0

Server: ChirpStack AS923 RAK831 gateway

Details:

We only choose this :

DownlinkDwellTime = 1

Can you modify a specific firmware which is unlocked DownlinkDwellTime for me? In another frequency plan, i can set dr to 0 (SF12). i want to use the maximum distance for some reasons.

No ,sorry to you !
We can not modify this DownlinkDwellTime!