In Toolbox Device Discovery Tool what does it say for IP address for the IDOCV? It needs to have it's own. Set it to an address for your system,(192.168.1.40 for example) make sure it's static so the MC3 can always find it, under the IP Table set it to IP ID 4 and either your MC3's hostname or actual IP address. In SIMPL set the Ethernet Upload address to the IP address of the IDOCV and the IP Net address should be 127.000.000.1