ftp proxy with nginx

hello,

I have a proxmox solution for virtualisation.
On each virtual machine there's a ftp service
On the node I put nginx (1.13) to proxy http/https between virtual machines and it's works well; but for FTP it does'nt work

1- Is it possible ?
2 - Has someone an example configuration ? (the idea is to use ftp.domain.fr to proxy on the first VM and ftp-preprod.domain.fr must be routed to & second VM

best
bruno