Problem with SF10 in US915

Hello forum
I have access to some rak2245 gateways from my university, some connected to version 2 and others to 3. As nodes I am using the TTGO ESP32 V0.7 and the “MCCI LoRaWAN LMIC Library”. As a test I used the ABP mode on the US915 frequency with the example that comes by default in the library. Both version 2 and version 3 nodes transmit well and I receive the information correctly. My problem is that when I adjust the SF with the LMIC_setDrTxpow (DR_SFX, 14) instruction, it works with the SF7, 8 and 9, and in the TTN metadata I have the corresponding SF value; however when I use the SF10, the metadata always shows me SF9. The problem occurs in both version 2 and 3. Do you know what the problem could be? I appreciate your collaboration.

How many bytes are you sending? If it is more than 11 bytes at SF10 you would exceed the 400ms dwell time limit. Your LMIC library may be smart enough to refuse to change to SF10 in this case. Could you test with a smaller message?

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yes, that was the problem, thank you very much

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