Rak4200 can not join via channel 64 ( US915)

at+get_config=lora:channel
OK 0,off,902300000,0,3; 1,off,902500000,0,3; 2,off,902700000,0,3; 3,off,902900000,0,3; 4,off,903100000,0,3; 5,off,903300000,0,3; 6,off,903500000,0,3; 7,off,903700000,0,3; 8,off,903900000,0,3; 9,off,904100000,0,3; 10,off,904300000,0,3; 11,off,904500000,0,3; 12,off,904700000,0,3; 13,off,904900000,0,3; 14,off,905100000,0,3; 15,off,905300000,0,3; 16,off,905500000,0,3; 17,off,905700000,0,3; 18,off,905900000,0,3; 19,off,906100000,0,3; 20,off,906300000,0,3; 21,off,906500000,0,3; 22,off,906700000,0,3; 23,off,906900000,0,3; 24,off,907100000,0,3; 25,off,907300000,0,3; 26,off,907500000,0,3; 27,off,907700000,0,3; 28,off,907900000,0,3; 29,off,908100000,0,3; 30,off,908300000,0,3; 31,off,908500000,0,3; 32,off,908700000,0,3; 33,off,908900000,0,3; 34,off,909100000,0,3; 35,off,909300000,0,3; 36,off,909500000,0,3; 37,off,909700000,0,3; 38,off,909900000,0,3; 39,off,910100000,0,3; 40,off,910300000,0,3; 41,off,910500000,0,3; 42,off,910700000,0,3; 43,off,910900000,0,3; 44,off,911100000,0,3; 45,off,911300000,0,3; 46,off,911500000,0,3; 47,off,911700000,0,3; 48,off,911900000,0,3; 49,off,912100000,0,3; 50,off,912300000,0,3; 51,off,912500000,0,3; 52,off,912700000,0,3; 53,off,912900000,0,3; 54,off,913100000,0,3; 55,off,913300000,0,3; 56,off,913500000,0,3; 57,off,913700000,0,3; 58,off,913900000,0,3; 59,off,914100000,0,3; 60,off,914300000,0,3; 61,off,914500000,0,3; 62,off,914700000,0,3; 63,off,914900000,0,3; *64,on,903000000,4,4; 65,off,904600000,4,4; 66,off,906200000,4,4; 67,off,907800000,4,4; 68,off,909400000,4,4; 69,off,911000000,4,4; 70,off,912600000,4,4; 71,off,914200000,4,4

at+join
ERROR: 91

at+join
ERROR: 91

at+join
ERROR: 91

So, No valid LoRa channel could be found. Channel 64 isn’t consider valid?

I turned on another normal 125khz channel and was able to join. I turned it off again so that channel 64 became the only one that was turned on:

at+get_config=lora:channel
OK 0,off,902300000,0,3; 1,off,902500000,0,3; 2,off,902700000,0,3; 3,off,902900000,0,3; 4,off,903100000,0,3; 5,off,903300000,0,3; 6,off,903500000,0,3; 7,off,903700000,0,3; 8,off,903900000,0,3; 9,off,904100000,0,3; 10,off,904300000,0,3; 11,off,904500000,0,3; 12,off,904700000,0,3; 13,off,904900000,0,3; 14,off,905100000,0,3; 15,off,905300000,0,3; 16,off,905500000,0,3; 17,off,905700000,0,3; 18,off,905900000,0,3; 19,off,906100000,0,3; 20,off,906300000,0,3; 21,off,906500000,0,3; 22,off,906700000,0,3; 23,off,906900000,0,3; 24,off,907100000,0,3; 25,off,907300000,0,3; 26,off,907500000,0,3; 27,off,907700000,0,3; 28,off,907900000,0,3; 29,off,908100000,0,3; 30,off,908300000,0,3; 31,off,908500000,0,3; 32,off,908700000,0,3; 33,off,908900000,0,3; 34,off,909100000,0,3; 35,off,909300000,0,3; 36,off,909500000,0,3; 37,off,909700000,0,3; 38,off,909900000,0,3; 39,off,910100000,0,3; 40,off,910300000,0,3; 41,off,910500000,0,3; 42,off,910700000,0,3; 43,off,910900000,0,3; 44,off,911100000,0,3; 45,off,911300000,0,3; 46,off,911500000,0,3; 47,off,911700000,0,3; 48,off,911900000,0,3; 49,off,912100000,0,3; 50,off,912300000,0,3; 51,off,912500000,0,3; 52,off,912700000,0,3; 53,off,912900000,0,3; 54,off,913100000,0,3; 55,off,913300000,0,3; 56,off,913500000,0,3; 57,off,913700000,0,3; 58,off,913900000,0,3; 59,off,914100000,0,3; 60,off,914300000,0,3; 61,off,914500000,0,3; 62,off,914700000,0,3; 63,off,914900000,0,3; *64,on,903000000,4,4; 65,off,904600000,4,4; 66,off,906200000,4,4; 67,off,907800000,4,4; 68,off,909400000,4,4; 69,off,911000000,4,4; 70,off,912600000,4,4; 71,off,914200000,4,4

at+send=lora:1:00010203
ERROR: 91

at+send=lora:1:00010203
ERROR: 91

at+send=lora:1:00010203
ERROR: 91

I wasn’t able to send anythig either. What’s wrong with this 500hz channel?

FWIW the LoRaWan specification strongly recommends transmitting join requests on both a 125 KHz channel and a 500 KHz one.

I could easily imagine the code assuming that at least one 125 KHz channel should be enable in accordance with the recommendation, even if it isn’t technically a spec “requirement”.

It’s an interesting question if you also enable a 125 KHz channel (and rig the network server not have the key needed to respond), are join requests transmitted on both that and the 500 KHz one, or only on the 125 KHz?

From my observation, It always use the 125KHZ channel when available, and gives we ERROR 91 when channel 64 was the only channel left on