Problem with RUI3 and Maximum Transmission Unit (MTU)

[Rodrigo]

I am using RUI3 version 3.4.2-rui3_22q1_update.112 on a RAK4630 board.
I have configured the board with the following AT commands:

AT+CLASS=A
AT+ADR=0
AT+DCS=0
AT+TXP=5
AT+BAND=6
AT+CHE=2
AT+CFM=0
AT+DR=0
AT+DEVEUI=16 hex numbers
AT+APPEUI=16 hex numbers
AT+APPKEY=32 HEX numbers
AT+NJM=1
AT+JOIN

The Join is successful. I can only send messages up to 11 bytes, whereas DR0 in the AU915 band allows up to 51 bytes. Why can’t I send the 51 bytes?

Thanks

[Rodrigo]

I have empirically reviewed the AU915 band, and the following are the supported data rates:

DR0: AT+DR=1 the modem returns AT_PARAM_ERROR
DR1: AT+DR=1 the modem returns AT_PARAM_ERROR
DR2: SF10BW125 → MTU (N): 11 bytes empirically validated
DR3: SF9BW125 → MTU (N) : 53 bytes empirically validated
DR4: SF8BW125 → MTU (N) : 175 bytes empirically validated
DR5: SF7BW125 → MTU (N) : 242 bytes empirically validated
DR6: SF8BW500 → MTU (N) : 242 bytes empirically validated

Perhaps there is a poorly constructed table with the regional parameters of the AU915 band.

I used this same card without RUI3 and it has no problems with MTUs in the AU915 band.

Does anyone else have the same problems?

[carlrowan]

Hi @Rodrigo ,

What you observe is normal on AU915. Those are limits imposed when Dwell Time is enabled.

You can try to check in your LNS if you can disable the dwell time from the network side.

[Rodrigo]

Thanks, Carl. That was the problem