Due to a problem with the Intel® Quartus® Prime Pro version 19.1, you may encounter the above critical warning when using the Triple-Speed Ethernet Intel® FPGA IP with LVDS I/O design when the default input termination
of LVDS reference clock is overridden by using the following QSF assignment or through the assignment editor.
set_instance_assignment -name INPUT_TERMINATION OFF -to ref_clk