The server socket in the tcpEcho example, while blocked on accept(), was showing "CLOSED". The expected state here is "LISTEN".

In the NDK stack, the transition to the "LISTEN" state doesn't happen until the listening socket receives a SYN request from a client. The if statement (that checks for a RX'd SYN) that encloses this state change also has a comment about the socket being in a listening state, although the code hasn't actually put it into that state yet:

Seems that the parent socket should have been put into the listening state during the listen call.