On my Kubuntu 11.10 machine  I have discovered that I cannot upload via FTP more than 5791 bytes. I have tried to two different FTP servers (not anonymous rather my employer's FTP servers) using Konqueror, GFTP, and Krusader. Also, to both of those servers other people can upload larger files just fine. I do not know if the issue is my Kubuntu desktop or possibly my router / ISP blocking. How might I troubleshoot that? I don't have any other computers here at home to FTP to / from.
I have no problem downloading larger files via SSH from this same machine.
 Still supported, and no I cannot upgrade to 12.04 at the moment.