Transfer timeout

When sending a file, it get to 100%, then delays (I assume a timeout), and then resends the entire file again. This continues over and over again. Anyone know a workaround or fix for this?

Please post the log from your transfers.

The server sends the wrong reply code or the reply code is cut by another network device (more likely):
[20:05:49] 6 Transfer complete.

It should be:
[20:05:49] 216 Transfer complete.