If nothing is being blocked by your ISP and the repository's URL hasn't changed, it might be worth trying to install the add-on directly from the original repository (if the current version came in a pack/build/wizard).
If that doesn't help, deleting Addon27.db from Android/data/org.xbmc.kodi/files/.kodi/userdata/Database , exiting Kodi then restarting has been recommended before I believe.