We had a virtual machine server setup for web, FTP was setup using Filezilla Server and all the ports were opened for PASV mode, which worked great for a number of months before suddenly without reason stopped working and dropped the connection as soon as the client requested to use PASV mode.
We scrapped this server in the end and we have since setup another server running IIS instead.
I again setup the PASV ports we wanted to use (5001-5005) and this was working fine for a couple weeks until today, and now the PASV mode has stopped working again. I've just opened a different set of ports (2501 - 2505) and set FTP to use this instead, but still the same issue. All firewalls and anti-viruses are disabled.
FileZilla client has this log:
Command: TYPE I
Response: 200 Type set to I.
Error: Disconnected from server: ECONNABORTED - Connection aborted
Error: Failed to retrieve directory listing
Using ACTIVE mode from a client works fine. Just the component we're using with C# only works with PASV