There is an unclear bug spotted recently in STM32F7 with FreeRTOS v2 and LWIP (ver. 2.1) library.
After a moment of using ethernet socket data stream soft hangs at this line:
configASSERT( pxQueue->uxItemSize == 0 );
It seems related to semaphore/mutex internal code issue. Could not find chance to dig too deep into it, but this post gave me a good hint:
I made the similar approach and made semaphore statically defined:
osSemaphoreId Netif_LinkSemaphore = NULL;
in the same lwip.c file.
So far it seemed to help with above problem.
Regarding other different issues with STM32 ethernet communication there is a nice compilation which might help us all: