Trying to mount nfs share on openwrt

Hi. I'm trying to mount an external nfs share in openwrt, but when I run:

mount -t nfs 192.168.1.3:/nfs /mnt/tmp -o nolock

I get "No such device" error. The same command mounts succesfully the share in an ubuntu machine.
I installed kmod-fs-nfs-common, kmod-fs-nfs-common-rpcsec, kmod-fs-nfsd, nfs-utils and nfs-utils-libs packages. I think that the correct modules are loaded:

root@OpenWrt:/# lsmod | grep nfs
auth_rpcgss            57344  2 nfsd,rpcsec_gss_krb5
grace                  16384  2 nfsd,lockd
lockd                  73728  1 nfsd
nfsd                  294912  0 
sunrpc                237568  4 nfsd,rpcsec_gss_krb5,auth_rpcgss,lockd

What is happening?. Any help would be appreciated. Thanks

EDIT: forgot to tell I am using current snapshot build in EA8500.

https://openwrt.org/docs/guide-user/services/nas/nfs.client#opkg_setup

Hi. Already did all the steps in that guide prior of writing here. In fact most of the packages shown there do not exist anymore:

root@OpenWrt:~# opkg install nfs-utils kmod-fs-nfs kmod-fs-nfs-v4 kmod-fs-nfs-v3
Package nfs-utils (2.5.4-4) installed in root is up to date.
Unknown package 'kmod-fs-nfs'.
Unknown package 'kmod-fs-nfs-v4'.
Unknown package 'kmod-fs-nfs-v3'.
Collected errors:
 * opkg_install_cmd: Cannot install package kmod-fs-nfs.
 * opkg_install_cmd: Cannot install package kmod-fs-nfs-v4.
 * opkg_install_cmd: Cannot install package kmod-fs-nfs-v3

Those packages do exist for the 5.4 kernel...

Run opkg update first.