@ChrisW67 Thank you for the reply but...

There is my interfaces states before AND after running the "example program" that actually works.
bc4dc02b-afdb-4680-a93c-812296f297aa-image.png

Where, in its code, the "example uses any interface including...".
Because I ran the "example" by disabling the "setSocketOption" line and replaced in the ipv4 socket bind "::AnyIPv4" with "::LocalHost" and it did not prevent the app from sending datagrams to the concerned broadcast address.

The solution that worked for me was to pick the network adapter and then look through its list of IP addresses to pick one to bind the socket to based on given criteria as suggested by @kshegunov. I've updated the example project:
https://github.com/rtavakko/MulticastServer

@TioRoy Obrigado pela resposta. Acabei fazendo com a biblioteca ffmpeg, pois consegui buscar os dados e jogar pra fora em multicast mas fica travando, estou errando em algum lugar.

Did you check with the latest Qt 5.5 if you still experience this behavior ?