Vieleicht hängt es auch einfach von der Implementierung des IoT-Gerätes ab.
https://punchthrough.com/android-ble-guide/
Zitat:
Unfortunately, we’ve also seen the onMtuChanged() callback not getting delivered sometimes when working with closed source firmware, which can put a damper on things if the app is relying on the callback being delivered before proceeding with something. Our advice is to always assume the worst case — that the ATT MTU is at its minimum value of 23 — and to plan around that when working with closed source firmware, with any successful onMtuChanged() calls being considered as added bonuses.
Ich bin nicht sicher ob der Event automatisch bei Verbindung gesendet wird, oder erst auf Anfrage nach requestMTU.