I'm running the S32K148EVB board with FreeRTOS and LWIP. I have a UDP echo task running on it and I test it under heavy UDP load from a computer. When the traffic I send is heavy enough the MCU stop receiving interrupts from the ENET controller (none of the ENET interrupts). I've checked the NVIC and ENET controllers and no ENET interrupts are disabled. If I enable the ENET controller accelerator to drop frames with MAC layer errors this does not happen anymore (at least not at the fastest traffic I managed).