• Regarding the MTU: Is an increased MTU size possible without Data Length extension?

    As you worded it I guess the answer is "no" but there is another BLE feature that allow sending bigger data i.e. write over 20 bytes to characteristics and receive it as single block. That feature is called "Write Long Characteristic" and "Read Long Characteristic". This works by splitting data to MTU sized chunks transparently on bluetooth stack level so both the calling code and receiving code gets it in one piece but still the MTU is 20 bytes and the data is splitted and reassembled for you.

    It would be useful if you figured out which type of write your device is using. If it negotiates for larger MTU via DLE or uses long writes over default 20 byte MTU.

    EDIT: posted before reading you next comment, in that case just forget it (if you trust what developers told you, they can be confused too and may in fact use long writes without knowing it)


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