Cut and paste this URL to share the unmodified register and value:
https://regviz.com/r/stm32/stm32n6/STM32N645/ETH/ETH_DMAC1TXRLR#0x0
Channel 1 T1 descriptor ring length register
Transmit Descriptor Ring Length
https://github.com/modm-io/cmsis-svd-stm32