Progress drop back near the ending and can't finish crack

[k79e]

Stats: 0:41:22 elapsed; 1032 services completed (2001 total)
Rate: 300.56; Found: 0; About 93.65% done; ETC: 16:26 (0:02:48 remaining)
Stats: 0:42:37 elapsed; 1956 services completed (2001 total)
Rate: 39.23; Found: 0; About 38.35% done; ETC: 17:33 (1:08:31 remaining)
Stats: 0:42:50 elapsed; 1962 services completed (2001 total)
Rate: 29.40; Found: 0; About 30.85% done; ETC: 18:00 (1:36:00 remaining)

...
tats: 0:46:45 elapsed; 1978 services completed (2001 total)
ate: 0.00; Found: 0; About 3.50% done; ETC: 13:59 (21:30:38 remaining)

At the same time I observed the program is still send packets at high speed (but not full speed)
I'm using those parameter on win7 x64
--user root --save save -P pw.txt -m ssh:cl=20,CL=300,at=4,cd=50ms,cr=2 -p ssh -iL iplist/inp.txt --connection-limit 400 --append-output -oN a1