I'm having issues with proftpd dropping connections after a very short amount of time.
All timeout settings in the configuration file and the router have been modified to prevent this from happening. For large files, the data connection stays alive, but the control connection dies after x minutes. After the data file finishes, the client just sits there not knowing what to do because it doesn't receive the proper response from proftpd on the control connection indicating that the transfer has completed.
I am being forced to perform PASV connections due to firewall restrictions on the server side.
Is this proftpd's fault, or is it the ISP's fault? How can I find out?