A failed upload of large files is a very generic error that could have multiple causes.
Basically, you could try and use a different browser (if you're not already on Chrome/Safari you should try one of those), as IE and FireFox are known to have some issues with memory/cache handling on large files uploads.
That said, did you use the drag&drop upload feature or the standard pop up form?
The best shot would be to try and use a browser supporting drag&drop features (like the two mentioned above), and try to upload the zipped files through that.
There is a file size limit of roughly 250MB for the upload pop up form, which is in place to prevent memory issues with browsers. But again, that could still happen.
Also if you're using a slow connection (say ~1MB upload speed), there's a high risk of losing network packets during the large files transfers from browser to the server. So if that's the case, try to upload files on a reliably strong and fast broadband connection.
Another couple of things you could check are:
- if on Fire Fox, you can change the timeout settings by typing "about:config" in the address bar and then filtering on "timeout": network.http.connection-timeout and check what's the amount of time for a timeout to be called. You should try to increase that (but probably want it to go back to default value once done).
- if on Chrome, you could also try to disable the network action prediction: Go to settings -> Show Advanced settings -> Privacy: uncheck the option that says 'Predict network actions to improve page load performance'. (Also roll it back to default once done).