Please download the link for testing
https://dl.dropboxusercontent.com/u/93374194/se.torrent
In my desktop can use this command to download

Aria2c/TMP/se. Torrent - d/TMP - o se. Iso
The same command role on openwrt

Aria2c/TMP/se. Torrent - d/TMP - o se. Iso
The Exception caught
Exception: [download_helper. Cc: 411] errorCode=1 Unrecognized URI or unsupported protocol:/TMP/se. Torrent

Please download the se. Torrent file, test on openwrt? !