Coding rate doesn't seem to be changing as expected

QUESTION: I'm assuming the command AT+FEC is for changing coding rate. I'm trying to change it from 4/5 to 4/8 by issuing AT+FEC=4, but I'm not seeing any coding rate change. Is this a bug?

ANSWER: In the LoRaWan 1.0.2 spec changelog (version 1.0.1 section), there was the following change:

"Introduced a requirement for using coding rate 4/5 in 7.2.2 to guarantee a maximum time on air < 400mSec"

The sx1272 datasheet says 4/5 cyclic coding rate corresponds to FEC/coding rate 1. So now FEC value of 1 is required.

Since changing the FEC/coding rate would now break compliance with the LoRaWan spec, it has disabled in current library and firmware and the AT commands/API calls will be removed in a later version.