download OpenWrt-ImageBuilder
untar and jump into directory
make image PROFILE=TLWA901 PACKAGES="-wpad-mini wpad luci zabbix-extra-mac80211 zabbix-extra-network zabbix-extra-wifi"
copy image into old running AP
scp ./bin/ar71xx/openwrt-15.05.1-ar71xx-generic-tl-wa901nd-v2-squashfs-fact ory.bin root@192.168.1.23:/tmp/
ssh into AP
ssh root@[ip] cd /tmp sysupgrade -b backup.tar.gz # backup old config sysupgrade -f ./backup.tar.gz ./openwrt-15.05.1-ar71xx -generic-tl-wa901nd-v2-squashfs-factory.bin # install new image and restore old config
configure zabbix
echo "zabbix:x:100:100:zabbix:/var:/bin/false" >> /etc/passwd
edit /etc/zabbix_agentd.conf