Why does the E-tile Hard IP for Ethernet FPGA IP change my Ethernet rate from 10G to 25G when I enable RSFEC in Quartus® Prime Pro Software version 18.0?

When using Quartus® Prime Pro Software version 18.0, and selecting '1 to 4 10GE/25GE with optional RSFEC' or '100GE or 1 to 4 10GE/25GE with optional RSFEC and 1588 PTP' core variants for the E-Tile Hard IP for Ethernet FPGA IP, the 'Select Ethernet Rate' parameter will be automatically switched from 10G to 25G when the 'Enable RSFEC' parameter is enabled.

The E-tile Hard IP for Ethernet FPGA IP do not have RSFEC support for any variant with 10G channels.

Users are advised not to select the "Enable RSFEC" option in 10G Ethernet rates as 10G speed mode is not supported in this core variant. Please refer to E-Tile Hard IP for Ethernet IP User Guide, figure 1, for supported variants of the IP.