Your responses to questions have not been clear enough for us to help.
"download accelerator" is a generic term and means different things on different platforms (windows/mac/linux).
When you upload, what program are you using? Given the size, I'm comfortable assuming you are not uploading through the browser to a php app (It's limited to 7 meg without gyrations).
Thus, we have to know what program "ftp" or "CuteFTP" or whatever program you're using is.
When you are downloading, there are some limits, but generally apache can handle downloads up to 2g without issues, I wouldn't suspect that this is your problem either.
Download accelerators often make use of multiple connections to download the same file faster. It is possible that you are opening more connections than the server is willing to let you have. DH is generally a shared environment and all the systems are configured to try to make access to all sites fair for all users. You might try turning it down to 1-3 concurrent connections and see if that helps prevent it from closing connections.
You really haven't given us the details we need to be of a lot of assistance and I've spent a sh*t-pot more time responding to your really vague and poorly thought out question. I do hope this helps, but if not, please give us more details and we'll try again.
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