Samsung M40 is a amazing phone and packs a bundle of good specs of SW and HW along with camera. However the major problem is non availability of 3.5mm jack which Samsung tried to solve providing it's own Type C headphone which sounds wonderful. As far as 3.5mm connectors are concerns I tried various connectors from differnt shops/ online and even connector from OnePlus, none of them works . I didn't tried any connector after upgrading to One UI 2.0. For OTG, it works fine on my phone. I have Type C to USB connector which I used for connecting Pen drives, Keyboard, Mouse etc. After lockdown I'll start my hunt for 3.5 mm connector again to check if any works on One UI 2.0. I provide updates on my page you can follow me there.