We used to have a simple PHY attached to the MII port and it seems the less you did to configure it the better. Now we have replaced it with a Marvell 10 port switch. Two of the ports have no phy and are setup to talk to the MII interface. My STM32 is doing a good job of sending ARPs but the IRQ in lwip.c never gets triggered. ETH_DMA_IT_R & ETH_DMA_IT_NIS are enabled but my status register has TBUS set which says "This bit indicates that the next descriptor in the transmit list is owned by the host and cannot
be acquired by the DMA. Transmission is suspended." RPS is 0b11, waiting, and TPS is 0b110, Suspended; Transmit descriptor unavailable or transmit buffer underflow. And unfortunately RS = 0; I know so little about ethernet in general so this thing is kicking my backside bigtime. So if you have some suggestions please speak/type slowly and use small words.