EM7455 ping timeout in uplink direction

IoT Modules MC/EM Series
3

I solved it.
After I chageed the OS, ping came to pass!

I test by connecting to the simulator.
I pinged a real machine, but pig does not pass.

So, when I changed form CentOS 6.9 to bunutu 9.10,
ping came to pass.

Thanks for help.