OpenWrt Chaos Calmer 15.05.1 on Fonera 2100, how to update package list

Hello,

I installed OpenWrt Chaos Calmer 15.05.1 (files from ath25-folder) on my foneras.
I cannot use a newer version of OpenWrt on these devices because LuCi is too slow and many browser-requests time out.
Because I want to use them in my private network as wifi-to-lan-bride, it's ok to use an old firmware.

My problem:
I cannot update package-list for instalable packages (software in LuCi, opkg update at ssh).

Error:

root@OpenWrt:~# opkg update
Package gst1-mod-gio version 1.4.5-1 has no valid architecture, ignoring.
Collected errors:
 * parse_from_stream_nomalloc: Missing new line character at end of file!
 * gz_close: Unzip process killed by signal 9.

 * gz_open: fork: Cannot allocate memory.
 * pkg_hash_add_from_file: Failed to open /var/opkg-lists/chaos_calmer_routing: Cannot allocate memory.
root@OpenWrt:~#

I tried to change the package feeds to this:

src/gz chaos_calmer_base http://archive.openwrt.org/chaos_calmer/15.05.1/ath25/generic/packages/base
src/gz chaos_calmer_luci http://archive.openwrt.org/chaos_calmer/15.05.1/ath25/generic/packages/luci
src/gz chaos_calmer_packages http://archive.openwrt.org/chaos_calmer/15.05.1/ath25/generic/packages/packages
src/gz chaos_calmer_routing http://archive.openwrt.org/chaos_calmer/15.05.1/ath25/generic/packages/routing
src/gz chaos_calmer_telephony http://archive.openwrt.org/chaos_calmer/15.05.1/ath25/generic/packages/telephony
src/gz chaos_calmer_management http://archive.openwrt.org/chaos_calmer/15.05.1/ath25/generic/packages/management

What do I have to do to get this working?
Packages are still available at https://archive.openwrt.org/chaos_calmer/15.05.1/ath25/generic/packages/

Thanks.

You are experiencing what it means to have insufficient resources to run OpenWrt.

Buy a new (or used) device with sufficient resources.