STM32F756G-EVAL 10 Mbps Half duplex not working

  /* Configure PA0
  GPIO_InitStructure.Pin =  GPIO_PIN_0;
  HAL_GPIO_Init(GPIOA, &GPIO_InitStructure);

  Note: Ethernet Full duplex mode works properly in the default setting
  (which MII_CRS is not connected to PA0 of STM32F756NGH6) because PA0 is shared
  with MC_ENA.
  If Half duplex mode is needed, uncomment PA0 configuration code source (above
  the note) and close the SB36 solder bridge of the STM32756G-EVAL board .
  */

  /* Configure PH3
  GPIO_InitStructure.Pin =  GPIO_PIN_3;
  HAL_GPIO_Init(GPIOH, &GPIO_InitStructure);

  Note: Ethernet Full duplex mode works properly in the default setting
  (which MII_COL is not connected to PH3 of STM32F756NGH6) because PH3 is shared
  with SDRAM chip select SDNE0.
  If Half duplex mode is needed, uncomment PH3 configuration code source (above
  the note) and close SB47 solder bridge of the STM32756G-EVAL board.
  */

  /* Configure PI10
  GPIO_InitStructure.Pin = GPIO_PIN_10;
  HAL_GPIO_Init(GPIOI, &GPIO_InitStructure);

  Note: Ethernet works properly in the default setting (which RX_ER is not
  connected to PI10 of STM32F756NGH6) because PI10 is shared with data signal
  of SDRAM.
  If RX_ER signal is needed, uncomment PI10 configuration code source (above
  the note) then remove R248 and solder SB9 of the STM32756G-EVAL board.
  */

Look at the source:

C:\Keil_v5\ARM\Pack\Keil\STM32F7xx_DFP\2.9.0\Projects\STM32756G_EVAL\Applications\LwIP\LwIP_HTTP_Server_Raw\Src\ethernetif.c

https://www.keil.com/boards2/stmicroelectronics/stm32756g_eval/#/eula-container