I couldn’t find a solution to unlock my situation, I tried many things on promox and on fog, without succes again. So I decided to start a new install on another post, separated from the proxmox and it’s working fine. I think I’ll keep this solution so, thanks for your help and sorry to leave an unsolved issue, see you later !
@Tom-Elliott to further iterate and give some more specific information.
Unicast worked because while the order was not “proper” it pulled the partition number from the iterated item. Example /dev/sda1 would look for file d1p1.img. /dev/sda10 would actually look for and use d1p10.img.
In multicast this iteration happens but the data is sent by the server.
It did not scan for a particular file.
So in your case the commands were sent in expected order.
udp-sender would send in order
d1p1.img, d1p2, d1p10
It sent the commands in that specific order. The partition receiving the file was not matching the file it was receiving. /dev/sda1 would get d1p1.img properly but /dev/sda10 was getting d1p2.img. Hopefully that helps make sense of the problem.