Could you try sniffing the ipv4 traffic?
And could you paste your .config somewhere?
Btw, a tiny detail:
[spi_context.h] ctx->config = 0x20000524You don't need CONFIG_ETH_ENC28J60_0_GPIO_SPI_CS on stm32 board, unless
you ant to use another gpio pin to act as the CS line.
CS logic works well on stm32 controllers.