Timeout problem using FileZilla FTP client with multiple simultaneous file uploads

For some strange reason FileZilla FTP client (version 3.3.5.1) kept producing timeout errors when trying to process multiple simultaneous file uploads. I was able to reproduce this behavior on Windows 7 Pro 64bit and Ubuntu Linux 11.04 64bit using the same version of FileZilla.

By default, FileZilla sets a maximum of 2 concurrent uploads. In my case, a quick fix was to simply set this value to 1, which directs FileZilla to upload files sequentially rather than simultaneously.

At this point I am not sure what causes this timeout problem, since it only occurs with one specific FTP server. Strange side fact: Other users are not reporting any symptoms of this kind on this server.

Anyhow, settings the max. concurrent upload count to 1 fixed the problem – for now.