I have a working board (ls1012a similar to frdm) that we have used for years with no issues with the 4.1.8 kernel from the Qoric SDK. I tried to move to the new LSDK 18.09 kernel pulled from the codeaurora (kernel 4.14.67), and although we can ping from the platform out with no issues, pinging from another host into the platform will lose packets. You can readily produce the loss with ping -f from a external host.
We have also tried other kernel versions. It seems to be related to the latest ppfe firmware or the pfe.ko device driver itself, as I can install the same kernel build on a different ARM platform and see no issues. The platform is very similar to the ls1012a FRDM board.
Do you see this issue?