I suggest that you use breakpoints and actually debug your code. Many of us here are willing to help on networking issues and even catch lwIP bugs, but it is sort of near to impossible to guess what the problem in your code is just by looking at a wireshark capture file.
I also suggest you download the examples in the contrib tree and study them. There you will see how a tcp_recv() callback has to work. tcp_recved() tells the stack you have taken care of the data, so it can manage ACKs, but to work, the stack needs to be called when an Ethernet frame (for example) arrives. You provide no info on what you are doing and how you call the stack, whether you are using bare metal or an RTOS, and I could guess you use the raw API because you mentioned tcp_recved() and tcp_recv(). Have you confirmed your tcp_recv() function is called on incoming frames and there is no delay there ? _______________________________________________ lwip-users mailing list lwip-users@nongnu.org https://lists.nongnu.org/mailman/listinfo/lwip-users