经实践，可行的一篇文章分享：

https://blog.csdn.net/shile/article/details/74392125

主要点子：

1、Passive mode settings的use custom port range 设置为50000到50002

2、frpc配置

[ftp21]

type = tcp

local_ip = 127.0.0.1

local_port = 21

remote_port = 2121





[ftp1]

type = tcp

local_ip = 127.0.0.1

local_port = 50000

remote_port = 50000





[ftp2]

type = tcp

local_ip = 127.0.0.1

local_port = 50001

remote_port = 50001





[ftp3]

type = tcp

local_ip = 127.0.0.1

local_port = 50002

remote_port = 50002

注意这里一定有四个，不然列表会报425的错误。