Cut and paste this URL to share the unmodified register and value:
https://regviz.com/r/stm32/stm32f1/STM32F101/ETHERNET_MMC/MMCCR#0x0
Ethernet MMC control register (ETH_MMCCR)
Counter reset
Counter stop rollover
Reset on read
MMC counter freeze
https://github.com/modm-io/cmsis-svd-stm32