i have try one thing.
In the raspberry i have put raspbian configure the ip to be the same of kodi
and i can type to mount the nfs share and i can see the directories
the problem is not the ip, not the server, it's seems that the rapbian that includes the libreelec. i'm in the beta New LibreELEC.tv Krypton build #0730
it's seems that the network in the raspbian not have something or configure something..... i will try to see the problem.....