For people with !SMALL_FLASH (i.e NOT 4MiB Flash devices) please test again with a up-to-date snapshot. Because
https://git.openwrt.org/?p=openwrt/openwrt.git;a=commit;h=fcb41decf6c622482b20af45a77e62db8d95046e
Enabled FHANDLE and friends, which from what I know prevented the nfs daemon from working in later releases.