Cut and paste this URL to share the unmodified register and value:
https://regviz.com/r/stm32/stm32f4/STM32F405/Ethernet_MAC/MACDBGR#0x0
Ethernet MAC debug register
CR
CSR
ROR
MCF
MCP
MCFHP
https://github.com/modm-io/cmsis-svd-stm32