Ok, had to do this:
root@Teltonika-RUT950:~# opkg remove ip --force-depends
Removing package ip from root...
Not deleting modified conffile /etc/iproute2/rt_tables.
Then this:
root@Teltonika-RUT950:~# opkg install ip-full
Installing ip-full (4.0.0-1) to root...
Downloading
http://downloads.openwrt.org/chaos_calmer/15.05.1/ar71xx/generic/packages/base/ip-full_4.0.0
-1_ar71xx.ipk.
Configuring ip-full.
Now, it works....
root@Teltonika-RUT950:~# ip tuntap help
Usage: ip tuntap { add | del | show | list | lst | help } [ dev PHYS_DEV ]
[ mode { tun | tap } ] [ user USER ] [ group GROUP ]
[ one_queue ] [ pi ] [ vnet_hdr ] [ multi_queue ]
Where: USER := { STRING | NUMBER }
GROUP := { STRING | NUMBER }
root@Teltonika-RUT950:~#
Ok, back to work.
Cheers,
John