http://bugs.winehq.org/show_bug.cgi?id=33008
--- Comment #13 from Erich Hoover erich.e.hoover@gmail.com --- (In reply to decimusmaximus from comment #12)
... If I understand it correctly, wine is listening on 0.0.0.0 and filters UDP datagrams according to bindings that are set by application. So if application does not want to listen on some interface, this traffic is filtered, but in this specific case (two interfaces, NAT) also the response is filtered out. Destination address of response belongs to network of IF-A (where application is not listening), but in this case response should be sent via IF-B, translated back in NAT and flow via IF-A to LAN network. But such UDP datagram is blocked by wine. ...
If you help me to do some testing I'd be happy to help fix this. This means that Wine is dropping the packet with the BPF that we're using to screen for interface-specific packets. Would it be possible for you to capture the packet meant for Wine with Wireshark and send me the packet? Also, what version of Wine are you running?