Art-net question with multiple sockets

ok that is not completely vvvv related; but i m facing little troubles in the developpement of an artnet new funny app in C.

perhaps someone could help me to figure out what is happening … this topic would be surely interresting for a lot of us, as its surely pointing troubles with more than one socket.

My trouble is around the ArtPoll function:
an ArtPoll call is made to detect by the app who is an ArtNet node on the network, get its IP and its nickname, etc…

I have finally founded my error in my code so now i can send real good artpoll message and receive normally the art poll reply of each node present.
Im monitoring with wireshark ( ex EtherAll) transit of data on one of the socket.

On my main computer, i m sending Art-Net to IP 2.255.255. in broadcast.
My computer has 2 socket network:
Enttec ODE is plugged to socket / sub DNS
Enttec ODE is set as

An other computer, hosting vvvv with 3 artnet differernt universes senders from the same patch is connected to my main computer on socket / sub DNS
I m receiving without troubles its 3 universes.

This computer has got the following socket adress: with sub and will not work if setted for example at: / sub DNS
This is my first question : WHY ?

My second artnet question is more vicious:
when making an artpoll, ( asking to see who is around on network):
I have only the Enttec ODE answering present, and one Packet ArtPollReply seen in Wireshark, wich is the ODE one.
If I unplug my Enttec ODE, I can see only 2 artpol reply from VVVV in my app. And with wireshark I may see 3 ArtpollReplies ( nickanme >-VVV@192.168.1. IP inside artpollreply: /
So sure I have a bug in my way of counting or receptionning artpoll replies ( or perhaps they are to quickly arriving and arriving when i m analysing the frame received)

My second question is : WHY cant i see VVVV replies and ENttec replies all together ?

should I use a switch ?

well thats all for today. Sure someone will explain me this strange thing and orient my way to plug or attribute adresses. do not hesitate to say “hey dude, its not like this…”

added a switch, connecting to it main computer, second computer, enttec ODE.
It enables to have a call back from everybody. So listening an artpollreply will be always from only one IP socket.

Any advices or any suggestion on how handle a multiple socket network ?