连接ftp的问题

连接ftp pure ftp 远程主机强迫关闭一个现有连接。消息是：
2017/12/18 13:40:05  Username:yy
2017/12/18 13:40:05  Stat> Connected.
2017/12/18 13:40:05  Recv> 220---------- Welcome to Pure-FTPd [privsep] ----------
2017/12/18 13:40:05        220-You are user number 2 of 50 allowed.
2017/12/18 13:40:05        220-Local time is now 13:40. Server port: 21.
2017/12/18 13:40:05        220-This is a private system - No anonymous login
2017/12/18 13:40:05        220-IPv6 connections are also welcome on this server.
2017/12/18 13:40:05        220 You will be disconnected after 15 minutes of inactivity.
2017/12/18 13:40:05  Sent> HOST [*.*.*.*](IP地址)
2017/12/18 13:40:24  Stat> Disconnected.
2017/12/18 13:40:24  Unable to load ftp://*******@*.*.*.*/: 远程主机强迫关闭了一个现有的连接。
2017/12/18 13:40:24  Load comparison:  <->

用xftp5 可以连接。