Re: [lwip-users] tcp_connection (no SYN packet on server side)

[Sergio R. Caprile]

OK, so it seems you are correctly calling lwIP in the loop, and your
networking parameters look good.
However, I failed to ask how do you setup your netif. You don't tell.
You should do something like this before actually calling tcp_connect():

  IP4_ADDR(&gw, 192,168,100,1);
  IP4_ADDR(&ipaddr, 192,168,100,250);
  IP4_ADDR(&netmask, 255,255,255,0);

  lwip_init();
  netif_add(&netif, &ipaddr, &netmask, &gw, perhaps NULL,
ethernetif_init, ethernet_input);
  netif_set_default(&netif);

Where your ethernetif_init() will properly init stuff...
        netif->output = etharp_output;
        netif->linkoutput = ethernetif_linkoutput;//driveroutputfunction

Can you fire a breakpoint at your ethernetif_output() and
ethernetif_linkoutput?