Hi folks, I'm working with the Boost Asio library from Boost 1.37 on Mac and Windows, and have encountered a problem that only occurs on Windows, and only when the computer has multiple network connections (such as both wired ethernet and WiFi). I started with the "HTTP Server" example code for a simple single- threaded server. I'm running the server on address 0.0.0.0 with port number 0 so that it listens on all network interfaces and allows the OS to select the port number. The server works fine on a Mac with multiple network connections. And on Windows, the default (wired ethernet) connection works fine, too. But if I try to connect to the Windows server over the non-default (WiFi) connection, there is about a 20 second pause and the server exits with error 121, "The semaphore timeout period has expired." I've done some poking around under the debugger, and it appears that the origin of this error is the AcceptEx call in the async_accept<> function in win_iocp_socket_service.hpp, line 2129. While this call does not fail directly since it is an asynchronous call, the error code eventually turns up in the accept_operation::do_completion_impl function in win_iocp_socket_service.hpp, line 1908. I don't really know enough about either Boost Asio or Windows networking to figure out much more on my own. Does anyone have an insight into the source of this problem, or suggestions on how I might go about tracking it down further? Best wishes, --Stuart A. Malone Llamagraphics, Inc. Makers of Life Balance personal coaching software http://www.llamagraphics.com/