TCP: Address already in use exception - possible causes for client port? NO PORT EXHAUSTION

Question

stupid problem. I get those from a client connecting to a server. Sadly, the setup is complicated making debugging complex - and we run out of options.

The environment:

Answer 1

"Address already in use", aka WSAEADDRINUSE (10048), means that when the client socket prepared to connect to the server socket, it first tried to bind itself to a specific local IP/Port pair that was already in use by another socket, either an active one or one that has been closed but is still in the FD_WAIT state. This has nothing to do with the number of ports that are available.