Nie wiem dlaczego się męczyłeś. Pokaż co wyświetla opkg update.
# opkg update
Downloading package list for attitude_adjustment source...
Package list for attitude_adjustment downloaded successfully.
Downloading package list for eko1 source...
Package list for eko1 downloaded successfully.
Downloading package list for gargoylepl_packages source...
Package list for gargoylepl_packages downloaded successfully.
# opkg install plugin-gargoyle-management
ERROR: No package named plugin-gargoyle-management found, try updating your package lists
# opkg list | grep plugin-gargoyl
plugin-gargoyle-3ginfo - 20131012 - 3ginfo for Gargoyle
plugin-gargoyle-logread - 20120724-4 - logread for Gargoyle
plugin-gargoyle-ping-watchdog - 20131030 - Ping Watchdog
plugin-gargoyle-theme-blue-ice-c - 20140112-1 - Blue Ice C Theme for Gargoyle
plugin-gargoyle-wifi-schedule - 1.1.2-2 - WiFi scheduling for Gargoyle