Additionally I had added a function HAL_ETH_SetMDIOClockRange() which is called from NetworkInterface.c
I believe HAL_ETH_SetMDIOClockRange() is already defined in the STM32Hxx/stm32hxx_hal_eth.c of +TCP V3.1.0.
Where is the ETH_TX_BUF_SIZE and ETH_RX_BUF_SIZE defined and to what value? Can you try using the FreeRTOSIPConfig.h used in the project linked by @htibosch.