Hi List.
I have socat 1.7.4.1-1 and the same version on Linux.
When I try to create a forking UDP server, only the first client is served, unlike in Linux where subsequent clients are served properly.

Test case. Terminal 1:

    socat -v UDP-LISTEN:12345,reuseaddr,fork SYSTEM:"stdbuf -i0 -o0 -e0 sed s/././g"

Terminal 2

    ( ( date; sleep 10 ) | socat UDP:127.0.0.1:12345 - & sleep 1; date | socat UDP:127.0.0.1:12345 - )

Expected output in Terminal 2:

    ...............................
    ...............................

Actual:

    ...............................

Reproducible: amd64, x86, Windows 10, Windows 7