torrent stuck on checked 0% and SLOWWW upload...

[EnderWood]

hi, really need help here...

when i add a torrent from a .torrent file, it start to download without issue... i leave it, and come back few min after... most of the time, the statut as change.
it have stop download and stuck at a "vérifié 0%" state (checked 0% i guess in english) like if i have stop and restart the torrent.

i try to stop and start again, but dont work. only way to fix i have found so far is cancel, start again, and pray this time it work. usualy need to remove and readd torrent 5/6 times before it work... when it work, download speed is perfect for my connexion

also, when a torrent is 100% downloaded, the upload speed is reaaaally slow, even with many leechers, like stuck at 10Ko/s with some "boost" up to 30Ko/s.. don't last long...
when i use windows client, i upload nead 700Ko/s

i have a LS duo 4t LS-WX4.0TL/R1
firemware 1.68
router and firewall ok (even try put the LS in DMZ to be sure but dont have change anything)

same issue with 6 different trackers...

really hope you can help me guys...