Bug? UDP Broadcast b4a

I made 2 small UDP clients for a program that I made before (using VB6 + winsock ocx) that broadcasts UDP messages on the x.x.x.255 adresse.
The one client is made with B4J v5.51 using jNetwork v1.20 as additional module. Works like a charm on Windows & OSX.
The other client is build with B4A v3.20 using the same jNetwork v1.20 additional module. Works well in "Debug Mode", but no in "Release Mode" : Some packets are received, some other not. If i put the desktop client and the Android device side by side, they work simultaneously when the Android app works on debug, but looses messages if in release mode.
I upgraded to B4A v7.30 and use the internal library "Network" v1.51 (switching to jNetwork 1.2 remains the same)
I get the same result :
Have you any idea about this change of behavior between release and debug mode ?

When it does not work: WHICH ERROR do you get? Check the Log (maybe the unfiltered log)

UDP broadcasting is unreliable by definition.
In debug mode the IDE communicates rapidly with the device so it probably helps the UDP messages to be transferred.

It's probably due to the broadcast address (for example 192.168.0.255). I thought that it was a bug, but it seems to be the implementation of the UDP stack on Android that is different than on other
(see : https://developer.android.com/reference/android/net/wifi/WifiManager.MulticastLock.html) and https://www.b4x.com/android/forum/t...y-v1-10-udp-supported.9099/page-3#post-154616)

if i just give the address of my device to the server's socket (for example 192.168.0.5) it works fine in "release mode" like in debug mode