Cut and paste this URL to share the unmodified register and value:
https://regviz.com/r/stm32/stm32h7/STM32H723/Ethernet_MAC/MMC_CONTROL#0x0
MMC control register
CNTRST
CNTSTOPRO
RSTONRD
CNTFREEZ
CNTPRST
CNTPRSTLVL
UCDBC
https://github.com/modm-io/cmsis-svd-stm32