First off, you're running a very outdated version of OpenWRT that has known security vulnerabilities in kernel, application software, and wireless. I'd upgrade before you go any further.
After you've upgraded to 17.01.4 or 18.06 (as 17.01 is about to be outdated), make sure you run opkg update before trying to install. That is typically the cause of being unable to find a "valid" package.
OK, it's a 16/32 device from the old wiki link you gave with a BCM6358KFBG SoC. Though tight on RAM, hopefully some life left in it for at least the 18.06 release, if you don't load it up with too many processes.
The old wiki gives the image as ../brcm63xx/generic/openwrt-brcm63xx-generic-AGV2%2bW-squashfs-cfe.bin
Running git bisect and looking for the change in the results of
lede_source$ fgrep -rI AGV2 target/linux/brcm63xx
suggest that your device might have had its "name" changed or not have been included in
Author: Álvaro Fernández Rojas <firstname.lastname@example.org>
Date: Tue May 24 21:09:19 2016 +0200
brcm63xx: move profiles definitions to image/Makefile
This switches brcm63xx to the new profile definition system in image/Makefile
Signed-off-by: Álvaro Fernández Rojas <email@example.com>