@MasterAntonio - Have you tried temporarily shutting off the firewall to see if that allows you to connect? If that works and you’re now able to connect, then we know the firewall is causing the connection to drop. From what I can see, firewall and/or anti-virus is one of the most common reasons for the connections dropping. I would disable on both sides (your PC/* and server).

@MasterAntonio - There’s a possibility, yes and it could be on either end. I know first-hand that the Windows Firewall is notorious for being problematic, and at random. I’ve ran in to far more issues as a result of Windows Firewall than I have with iptables. At least with iptables is generally user-error unless there was an issue to begin with.

Coming direct from one of the developers of FileZilla, firewalls & anti-virus are known to cause issues, which can result in idle connections being dropped.