[OpenWrt Wiki] OpenWrt 15.05.1 "Chaos Calmer"
https://openwrt.org/releases/15.0503.03.2018 · OpenWrt 15.05.1 "Chaos Calmer" The OpenWrt Chaos Calmer release series is the latest supported stable release of the OpenWrt project before the LEDE/OpenWrt project merger. Latest Chaos Calmer Release - OpenWrt 15.05.1 The most recent Chaos Calmer version is OpenWrt 15.05.1, the first service release of the OpenWrt 15.05 series.
OpenWrt Forum Archive
https://forum.archive.openwrt.org/viewtopic.php?id=6393504.04.2016 · Yes it is a fresh upgrade from Openwrt Designated Driver to Openwrt Chaos Calmer 15.05 which has been done via web interface.After restarting, the router could be ping via 192.168.1.1/24 but for ssh it is forced me to put password. Further more the luci web interface has not installed yet because I could not enter to the router to install GUI.