socket for detection UDP-based protocol

I made a Windows tool to discover DIGIs on the network using UDP messages, even when they are in AutoIp mode and the IP doesn’t match with the computer IP.

My problem is the following:
If computer IP is and the DIGI is (retrieved from AutoIP), the DIGI receive the message but doesn’t want to send back the answer (error #118, Host is unreachable).

It works well if the DIGI is in the same subnet.
It worked well too when I was using FastIp API in NETOS60F, which is no more available.

I tried the “SO_DONTROUTE” socket option or the MSG_DONTROUTE flag, but it doesn’t work. Do you know how to do?

Thanks for your information…


You could use the Ethernet Bypass function to put the data on the wire directly.