The reference clk of lpddr2 is connected to the output of pll, the project can compile success in 17.1 but failed in 13.1.
Error: Failed to find PLL reference clock.
Probably it is due to an issue for that old version. The 13.1 obsolete quartus version is obsoleted. Please use newer version.
For more complete information about compiler optimizations, see our Optimization Notice.